Artificial leather and method for manufacturing same, vehicular interior material, vehicular component, miscellaneous goods, and furniture

Abstract

The present invention addresses the problem of providing an artificial leather having excellent moldability that allows the artificial leather to easily follow complicated shapes, and excellent surface quality after being molded. The present invention pertains to an artificial leather comprising: a base material part that includes a polymer elastic body and a fiber entangled body including a nonwoven fabric made of ultrafine fibers having an average monofilament diameter of 0.01-10.00 μm; and a napped part on at least one surface of the artificial leather. The mass proportion of the polymer elastic body in the artificial leather is 15-40 mass%. The area proportion of the polymer elastic body on the surface of the artificial leather on which the napped part is present is 0.01-3.00%. The area proportion of the polymer elastic body in a cross-section of the artificial leather is not less than 5% but less than 15%.

Description

Artificial leather and its manufacturing method, vehicle interior materials, vehicle parts, miscellaneous goods and furniture

[0001] The present invention relates to artificial leather and a method for producing the same, vehicle interior materials, vehicle parts, miscellaneous goods, and furniture.

[0002] Artificial leathers made of a fiber-entangled structure and a polymeric elastomer such as polyurethane have superior characteristics compared to natural leathers, such as high durability and uniform quality. For this reason, they are used in a variety of fields, including interior materials for vehicles such as automobiles, aircraft, and railroad cars, interior items such as furniture, clothing, and even miscellaneous goods such as shoes and bags. When artificial leathers are used as the surface of vehicle interior materials and interior items, they are required to be moldable so that they can easily conform to complex shapes, and various artificial leathers have been proposed.

[0003] For example, Patent Document 1 proposes a method for producing stretchable artificial leather, in which an artificial leather composed of polyurethane and a fiber-entangled structure mainly containing ultrafine fibers with a single fiber fineness of 1.1 dtex or less is stretched in the length direction and contracted in the width direction in a heated state after or simultaneously with the application of a softener to the artificial leather. It is described that this method makes it possible to provide an artificial leather that is excellent in both stretchability in the width direction and flexibility at low cost by a simple method.

[0004] Patent Document 2 proposes an artificial leather comprising a fiber sheet and a polyurethane resin, in which the cross-sectional polyurethane resin area ratio in the thickness direction cross section of a fiber layer (A) constituting a first outer surface of the artificial leather in the fiber sheet and the standard deviation of the cross-sectional polyurethane resin area ratio are within a specific range. According to this document, it is stated that this artificial leather has excellent texture (stiffness / softness value) and wrinkle resistance, and is therefore suitable for use in upholstery or interior materials for seats for interiors, automobiles, aircraft, railway vehicles, etc., as well as for clothing products.

[0005] Japanese Patent Publication No. 2005-76151 Japanese Patent Publication No. 2021-70904

[0006] The technology disclosed in Patent Document 1 allows the artificial leather to exhibit stretchability in the width direction. This allows the artificial leather to be molded and processed to a certain extent in the width direction to fit complex shapes such as those of vehicle interior materials and interiors. However, it is not possible to make the artificial leather conform sufficiently in the length direction to fit complex shapes. In other words, the resulting artificial leather tends to have anisotropy, which can easily cause the raised nap on the surface of the artificial leather to crack in places, exposing the polymeric elastomer from those places and resulting in a deterioration in surface quality.

[0007] In addition, in the technology disclosed in Patent Document 2, the cross-sectional polyurethane resin area ratio and its standard deviation in the thickness direction of the fiber layer constituting the outer surface of the artificial leather are set within a predetermined range. This increases the density of the polyurethane that forms a membrane-like structure, and even when using a water-dispersible polyurethane resin that tends to form a non-porous membrane, it is possible to achieve a certain level of texture and wrinkle resistance. However, if the cross-sectional polyurethane resin area ratio is approximately 15% or more and 30% or less, the artificial leather tends to stretch or tear locally when molded into a complex shape. This can result in exposure of the polyurethane from areas where the napped portion on the surface of the artificial leather cracks, which can also lead to a decrease in surface quality.

[0008] The present invention has been made in view of the above circumstances, and its object is to provide an artificial leather that has excellent formability so that it can easily conform to even complex shapes, and that also has excellent surface quality after molding.

[0009] As a result of extensive research conducted by the present inventors to achieve the above-mentioned object, they discovered that by setting the mass proportion of the polymer elastomer in the artificial leather and the area proportion of the polymer elastomer on the surface and cross section of the artificial leather within specific ranges, it is possible to obtain artificial leather that has good formability that allows it to conform to even complex shapes, and that retains a dense and smooth surface quality even after molding, thereby arriving at the present invention.

[0010] The present invention has been completed based on these findings, and provides the following inventions.

[0011] [1] An artificial leather having a base material including a fiber-entangled body containing a nonwoven fabric made of ultrafine fibers having an average single fiber diameter of 0.01 μm or more and 10.00 μm or less, and a polymeric elastomer, and a napped portion on at least one surface, wherein the mass ratio of the polymeric elastomer to the artificial leather is 15 mass% or more and 40 mass% or less, the area ratio of the polymeric elastomer to at least one surface of the artificial leather having the napped portion is 0.01% or more and 3.00% or less, and the area ratio of the polymeric elastomer to a cross section of the artificial leather is 5% or more and less than 15%.

[0012] [2] The artificial leather according to [1], wherein the standard deviation of the area ratio of the polymeric elastomer on at least one surface of the artificial leather having the napped portion is 25% or less.

[0013] [3] The artificial leather according to [1] or [2], wherein the standard deviation of the area ratio of the polymeric elastomer in the cross section of the artificial leather is 25% or less.

[0014] [4] The thickness t of the base material Ａ is 250 μm or more and 800 μm or less, and the thickness t of the base material Ａ and the thickness of the raised part t Ｂ Ratio to t Ａ / t Ｂ The artificial leather according to any one of [1] to [3], wherein the value is 0.5 or more and 2.5 or less.

[0015] [5] The thickness t of the base material Ａ The artificial leather according to [4], wherein the coefficient of variation of the above is 50% or less.

[0016] [6] The artificial leather according to any one of [1] to [5], wherein the ultrafine fibers contain a black pigment.

[0017] [7] A method for producing an artificial leather, comprising the steps of: imparting polyvinyl alcohol to a fiber-entangled body containing a nonwoven fabric mainly composed of ultrafine fiber-developing fibers in an amount of 4% by mass to 40% by mass, relative to the mass of the ultrafine fiber-developing fibers, to form a polyvinyl alcohol-imparted sheet; expressing ultrafine fibers having an average single fiber diameter of 0.01 μm to 10.00 μm from the ultrafine fiber-developing fibers of the polyvinyl alcohol-imparted sheet to form a nonwoven sheet; expanding the width of the nonwoven sheet by 2% to 10% to form an expanded sheet; imparting a polymeric elastomer to the expanded sheet in an amount of 12% by mass to 64% by mass, relative to the mass of the expanded sheet, to form a polymeric elastomer-imparted sheet; removing the polyvinyl alcohol from the polymeric elastomer-imparted sheet to form a base sheet; and grinding at least one surface of the base sheet.

[0018] [8] A method for producing an artificial leather, comprising the steps of: imparting polyvinyl alcohol to a fiber-entangled body containing a nonwoven fabric mainly composed of ultrafine fiber-developing fibers in an amount of 4% by mass to 40% by mass, relative to the mass of the ultrafine fiber-developing fibers, to form a polyvinyl alcohol-imparted sheet; expanding the width of the polyvinyl alcohol-imparted sheet by 2% to 10% to form an expanded sheet; expressing ultrafine fibers having an average single fiber diameter of 0.01 μm to 10.00 μm from the ultrafine fiber-developing fibers of the expanded sheet to form a nonwoven sheet; imparting a polymeric elastomer to the nonwoven sheet in an amount of 12% by mass to 64% by mass, relative to the mass of the nonwoven sheet, to form a polymeric elastomer-imparted sheet; removing the polyvinyl alcohol from the polymeric elastomer-imparted sheet to form a base sheet; and grinding at least one surface of the base sheet.

[0019] [9] The method for producing an artificial leather according to [7] or [8], wherein in the step of forming the polyvinyl alcohol sheet, polyethylene glycol is contained in an amount of 0.01% by mass or more and 0.5% by mass or less relative to the mass of the polyvinyl alcohol.

[0020]

[10] A vehicle interior material comprising the artificial leather according to any one of [1] to [6].

[0021]

[11] A vehicle part comprising the artificial leather according to any one of [1] to [6].

[0022]

[12] Miscellaneous goods comprising the artificial leather according to any one of [1] to [6].

[0023]

[13] Furniture comprising the artificial leather according to any one of [1] to [6].

[0024] According to the present invention, it is possible to obtain artificial leather that has excellent moldability, allowing it to easily conform to even complex shapes, and that also has excellent surface quality after molding.The artificial leather of the present invention can be used in a wide range of applications, including vehicle interior materials, vehicle parts, miscellaneous goods, furniture, and clothing, but because of its excellent moldability, allowing it to easily conform to even complex shapes, and also has excellent surface quality after molding, it is particularly suitable for applications such as vehicle interior materials, vehicle parts, miscellaneous goods, and furniture.

[0025] Fig. 1 is a cross-sectional view of an artificial leather according to the present invention. Ａ , thickness of the piled portion t Ｂ FIG. 2 is a cross-sectional conceptual diagram for explaining a method for measuring the coefficient of variation.

[0026] The artificial leather of the present invention has a substrate including a fiber-entangled structure containing a nonwoven fabric made of ultrafine fibers having an average single fiber diameter of 0.01 μm to 10.00 μm and a polymeric elastomer, and a napped portion on at least one surface, wherein the mass percentage of the polymeric elastomer in the artificial leather is 15% to 40% by mass, the area percentage of the polymeric elastomer in at least one surface of the artificial leather having the napped portion is 0.01% to 3.00%, and the area percentage of the polymeric elastomer in the cross section of the artificial leather is 5% to less than 15%. These components will be described in detail below, but the present invention is not limited to the scope described below as long as it does not deviate from the gist of the invention, and various modifications are possible without departing from the gist of the invention.

[0027] [Fiber-entangled body] The substrate portion of the artificial leather according to one embodiment of the present invention (hereinafter also referred to as "the present embodiment") first includes a fiber-entangled body containing a nonwoven fabric made of ultrafine fibers having an average single fiber diameter of 0.01 μm or more and 10.00 μm or less.

[0028] The ultrafine fibers of this nonwoven fabric are preferably composed primarily of a melt-spinnable thermoplastic resin. Examples of such thermoplastic resins include polyesters such as polyethylene terephthalate, polytrimethylene terephthalate, polytetramethylene terephthalate, and polylactic acid; polyamides such as polyamide 6, polyamide 66, and polyamide 12; acrylic; polyolefins such as polyethylene and polypropylene; polyphenylene sulfide (PPS); and thermoplastic cellulose. Among these, polyester-based resins are preferred from the viewpoints of strength, dimensional stability, and light resistance. In this embodiment, the term "main component" refers to a component whose content accounts for 50% or more by mass of the constituent elements. For example, "the main component of the ultrafine fibers is polyethylene terephthalate" means that 50% or more by mass of the ultrafine fiber components is polyethylene terephthalate.

[0029] Examples of the polyester resin include polyethylene terephthalate, polytrimethylene terephthalate, polytetramethylene terephthalate, as well as polycyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, and polyethylene-1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate. Among these, polyethylene terephthalate, which is the most widely used, or a polyester copolymer containing primarily ethylene terephthalate units is preferably used. In this embodiment, "polyester copolymer containing primarily ethylene terephthalate units" refers to a polyester copolymer containing 80 mol% or more of ethylene terephthalate units, whose copolymerization component is isophthalic acid or bisphenol A.

[0030] Furthermore, as the polyester-based resin, a single polyester may be used, or two or more different polyesters may be blended together. When two or more different polyesters are blended together, the difference in intrinsic viscosity (IV value) of the polyesters used is preferably 0.50 or less, and more preferably 0.30 or less, from the viewpoint of compatibility between the two or more components.

[0031] In the present invention, the intrinsic viscosity is calculated by the following method: (1) 0.8 g of a sample polymer is dissolved in 10 mL of orthochlorophenol. (2) The relative viscosity η is measured using an Ostwald viscometer at a temperature of 25°C. ｒ Calculate using the formula below and round off to the third decimal place η ｒ = η / η ０ = (t × d) / (t ０ ×d ０ ) ... (formula) Intrinsic viscosity (IV value) = 0.0242η ｒ +0.2634 ... (formula) (where η is the viscosity of the polymer solution, η ０ is the viscosity of orthochlorophenol, t is the solution drop time (seconds), and d is the solution density (g / cm ３ ), t ０ is the fall time of orthochlorophenol (seconds), d ０ is the density of orthochlorophenol (g / cm ３ ) and ).

[0032] From the viewpoint of processing operability, the cross-sectional shape of the ultrafine fibers is preferably round (a cross-sectional shape that is a perfect circle); however, other shapes can also be adopted in accordance with desired properties, such as oval, capsule-like, polygonal (including shapes with rounded corners) shapes, fan-shaped, cross-shaped, hollow, Y-shaped, T-shaped, and U-shaped cross-sectional shapes.

[0033] In this embodiment, the average single fiber diameter of the ultrafine fibers is 0.01 μm or more and 10.00 μm or less. When the average single fiber diameter of the ultrafine fibers is 0.01 μm or more, preferably 1.00 μm or more, the artificial leather exhibits excellent effects in color development after dyeing, light fastness and friction fastness, and stability during spinning. On the other hand, when the average single fiber diameter of the ultrafine fibers is 10.00 μm or less, preferably 5.00 μm or less, the artificial leather exhibits a smooth feel and a dense surface quality.

[0034] In this embodiment, the average single fiber diameter of ultrafine fibers is calculated by taking an SEM image of the cross section of the artificial leather using a scanning electron microscope (SEM, for example, Model VHX-D500 / D510 manufactured by Keyence Corporation. Hereinafter, when a measuring device is exemplified in the description of the measurement method, it means that the exemplified device or a device with equivalent performance is used for the measurement), randomly selecting 10 circular or elliptical ultrafine fibers close to a circle, measuring the single fiber diameters, calculating the arithmetic average of the 10 fibers, and rounding off to one decimal place. However, when ultrafine fibers with a modified cross section are used, the cross-sectional area of ​​the single fiber is first measured, and the diameter of the single fiber is found by calculating the diameter when the cross section is considered to be circular.

[0035] To the resin forming the ultrafine fibers, various additives may be added according to various purposes, within the scope of not impairing the object of the present invention, such as black pigments described below, chromatic fine particle oxide pigments such as "iron oxyhydroxide and cobalt aluminate," inorganic particles such as titanium oxide particles, lubricants, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage agents, and antibacterial agents.

[0036] In particular, in this embodiment, in order to achieve both deep and uniform color development, it is preferable that the ultrafine fibers contain a black pigment. As this black pigment, a carbon-based black pigment such as "carbon black or graphite" or an oxide-based black pigment such as "a composite oxide of triiron tetroxide, copper, and chromium" can be used. In particular, it is more preferable that the black pigment is carbon black, as this makes it easier to obtain a black pigment with a small particle size and has excellent dispersibility in polymers.

[0037] When the ultrafine fibers contain a black pigment, the average particle size of the black pigment is preferably 0.05 μm or more and 0.20 μm or less. The average particle size of the black pigment here refers to the average particle size of the black pigment when it is present in the ultrafine fibers, which is generally called the secondary particle size, i.e., the average particle size in an aggregated state.

[0038] By setting the average particle size of the black pigment to preferably 0.05 μm or more, more preferably 0.07 μm or more, the black pigment is retained inside the ultrafine fibers, thereby preventing the pigment from falling off from the ultrafine fibers. This results in an artificial leather with excellent abrasion resistance. Furthermore, by setting the average particle size of the black pigment to preferably 0.20 μm or less, more preferably 0.18 μm or less, and even more preferably 0.16 μm or less, it is possible to prevent the pigment from being exposed to the surface of the ultrafine fibers, and to achieve excellent stability during spinning and excellent yarn strength, resulting in an artificial leather with excellent abrasion resistance and strength.

[0039] Furthermore, when the ultrafine fibers contain a black pigment, the coefficient of variation (CV) of the particle size of the black pigment is preferably 75% or less. When the coefficient of variation (CV) of the particle size of the black pigment is 75% or less, preferably 65% ​​or less, more preferably 60% or less, even more preferably 55% or less, and most preferably 50% or less, the particle size distribution becomes narrow, and exposure of the pigment on the surface of the ultrafine fibers, detachment of small particles from the surface, poor spinning due to significant particle aggregation, and a significant decrease in yarn strength are suppressed. Note that, although there is no particular restriction on the lower limit of the coefficient of variation of the particle size in this embodiment, from the viewpoint of spinning operability and production costs, 0.1% or more is preferred.

[0040] In this embodiment, the average particle size and coefficient of variation (CV) of the black pigment are calculated by the following method. (1) Ultrathin sections with a thickness of 5 μm to 10 μm are prepared in the cross-sectional direction of a surface perpendicular to the longitudinal direction of the ultrafine fibers. For example, an ultramicrotome "MT6000" manufactured by Sorvall can be used to prepare these ultrathin sections. (2) The cross section of the fiber in the ultrathin section is observed at 10,000x magnification using a transmission electron microscope (TEM, for example, "H7700" manufactured by Hitachi High-Technologies Corporation). (3) Using image analysis software (for example, "WinROOF" manufactured by Mitani Corporation), the circle-equivalent diameter of the particle size of the black pigment at 20 points within a 2.3 μm × 2.3 μm field of view of the observed image is measured. If there are fewer than 20 black pigment particles within a 2.3 μm × 2.3 μm field of view, measure the circle-equivalent diameters of all the black pigment particles present. (4) Calculate the average (arithmetic mean) and coefficient of variation (CV) for the particle diameters measured at the 20 points. In this embodiment, the coefficient of variation is calculated using the following formula: Coefficient of variation of particle diameter (%) = (standard deviation of particle diameter) / (arithmetic mean of particle diameter) × 100 (formula).

[0041] Furthermore, when the ultrafine fibers contain a black pigment, the content of the black pigment in the resin forming the ultrafine fibers is preferably 0.1% by mass or more and 5.0% by mass or less, and more preferably 2.0% by mass or more and 5.0% by mass or less, relative to the mass of the ultrafine fibers. By setting the pigment content to 0.1% by mass or more, preferably 1.0% by mass or more, more preferably 2.0% by mass or more, even more preferably 2.5% by mass or more, and most preferably 3.0% by mass or more, artificial leather with excellent dark color development can be obtained. By setting the pigment content to 5.0% by mass or less, preferably 4.5% by mass or less, and more preferably 4.0% by mass or less, artificial leather with excellent physical properties such as strength and elongation can be obtained.

[0042] In this embodiment, the content of black pigment contained in the resin forming the ultrafine fibers is calculated by the following method: (1) Immerse artificial leather in a solution containing dimethylformamide or the like to remove the polymer elastomer and collect ultrafine fibers. (2) For the collected ultrafine fibers, dissolve the resin using a mixture of phenol and tetrachloroethane to extract only the black pigment. (3) Perform evolved gas analysis on the extracted black pigment and create a calibration curve for the evolved gas derived from the black pigment. (4) After dedying the artificial leather, extract the polymer elastomer using dimethylformamide or the like to leave only the ultrafine fibers, and then collect the ultrafine fibers. (5) Perform evolved gas analysis on the collected ultrafine fibers and calculate the proportion of black pigment contained in the ultrafine fibers from the detected intensity of the evolved gas derived from the black pigment and the calibration curve created in (3).

[0043] The fiber-entangled body of the artificial leather of this embodiment includes a nonwoven fabric made of the ultrafine fibers.

[0044] In this embodiment, the term "a fiber-entangled body including a nonwoven fabric" refers to an embodiment in which the fiber-entangled body is a nonwoven fabric, or an embodiment in which a nonwoven fabric and a woven fabric are entangled and integrated together as described below, or an embodiment in which a fiber-entangled body is entangled and integrated with a nonwoven fabric and a substrate other than a woven fabric.

[0045] By forming a fiber entanglement body containing a nonwoven fabric, it is possible to obtain a uniform and elegant appearance and texture when the surface is raised.

[0046] The nonwoven fabric may be in the form of a long-fiber nonwoven fabric mainly composed of filaments, or a short-fiber nonwoven fabric mainly composed of fibers of 100 mm or less. When a short-fiber nonwoven fabric is used, more fibers can be oriented in the thickness direction of the artificial leather than when a long-fiber nonwoven fabric is used. This allows the surface of the artificial leather to have a high density and a good feel when raised.

[0047] When a short-fiber nonwoven fabric is used, the fiber length of the ultrafine fibers is preferably 25 mm or more and 95 mm or less. By setting the fiber length to 95 mm or less, more preferably 85 mm or less, and even more preferably 75 mm or less, the artificial leather will have an excellent texture and a dense, smooth surface. On the other hand, by setting the fiber length to 25 mm or more, more preferably 35 mm or more, and even more preferably 40 mm or more, the artificial leather will have excellent abrasion resistance.

[0048] In the artificial leather of this embodiment, for the purpose of improving its strength and shape stability, a woven fabric may be laminated inside or on one side of the nonwoven fabric and intertwined with it.

[0049] The type of fiber constituting the woven fabric used when entangling and integrating the above-mentioned woven fabrics is preferably a filament yarn, a spun yarn, a composite yarn made of a filament yarn and a spun yarn, etc. Among these, from the viewpoint of durability, particularly mechanical strength, it is more preferable to use a multifilament containing a polyester resin or a polyamide resin as a main component.

[0050] The average single fiber diameter of the fibers constituting the woven fabric is preferably 1.0 μm or more and 50.0 μm or less. By having the average single fiber diameter of the fibers constituting the woven fabric be preferably 50.0 μm or less, more preferably 15.0 μm or less, and even more preferably 13.0 μm or less, an artificial leather with excellent flexibility can be obtained. Furthermore, even if the fibers of the woven fabric are exposed on the surface of the artificial leather, the hue difference with the pigment-containing ultrafine fibers after dyeing is small, resulting in an artificial leather with an unimpaired surface hue uniformity. On the other hand, by having the average single fiber diameter of the fibers constituting the woven fabric be preferably 1.0 μm or more, more preferably 8.0 μm or more, and even more preferably 9.0 μm or more, an artificial leather with higher dimensional stability can be obtained.

[0051] In this embodiment, the average single fiber diameter of the fibers constituting the woven fabric is calculated by taking an SEM image of the cross section of the artificial leather using a scanning electron microscope (SEM, for example, Model VHX-D500 / D510 manufactured by Keyence Corporation), randomly selecting 10 fibers constituting the woven fabric, measuring the single fiber diameters of the selected fibers, calculating the arithmetic average value of the 10 fibers, and rounding off the result to one decimal place.

[0052] When the fibers constituting the woven fabric are multifilaments, the total fineness of the multifilaments is measured by "8.3.1 Correct fineness b) Method B (simplified method)" of "8.3 Fineness" of JIS L1013:2010 "Testing methods for chemical fiber filament yarns," and is preferably 30 dtex or more and 170 dtex or less.

[0053] When the total fineness of the yarns constituting the woven fabric is 170 dtex or less, the artificial leather has excellent flexibility. On the other hand, when the total fineness is 30 dtex or more, the artificial leather has higher shape stability. Furthermore, when the nonwoven fabric and the woven fabric are entangled and integrated by needle punching or the like, the fibers constituting the woven fabric are less likely to be exposed on the surface of the artificial leather, resulting in an artificial leather with high surface quality. In this case, it is preferable that the total fineness of the warp and weft multifilaments is the same.

[0054] Furthermore, the twist number of the yarns constituting the woven fabric is preferably 1000 T / m or more and 4000 T / m or less. By setting the twist number to preferably 4000 T / m or less, more preferably 3500 T / m or less, and even more preferably 3000 T / m or less, the artificial leather will have excellent flexibility. On the other hand, by setting the twist number to preferably 1000 T / m or more, more preferably 1500 T / m or more, and even more preferably 2000 T / m or more, damage to the fibers constituting the woven fabric can be prevented when the nonwoven fabric and the woven fabric are entangled and integrated by needle punching or the like, thereby resulting in an artificial leather with excellent mechanical strength.

[0055] [Elastomer] The substrate of the artificial leather of this embodiment further contains an elastomer.

[0056] Examples of the polymeric elastomer include polyurethane, polyurea, polyurethane-polyurea, and polyacrylic. The polymeric elastomer functions as a binder that holds the ultrafine fibers contained in the artificial leather. Therefore, in consideration of the soft texture of the artificial leather of this embodiment, it is preferable that the polymeric elastomer used be polyurethane.

[0057] This polyurethane is obtained by reacting a polymer diol, an organic diisocyanate, and a chain extender, and can be either an organic solvent-based polyurethane, which is used in a dissolved state in an organic solvent, or a water-dispersed polyurethane, which is used in a dispersed state in water.

[0058] When the polymeric elastomer is polyurethane, the polymer diol may be, for example, a polycarbonate-based diol, a polyester-based diol, a polyether-based diol, a silicone-based diol, or a fluorine-based diol. A copolymer of these may also be used. Among these, from the viewpoints of hydrolysis resistance and abrasion resistance, it is preferable to use a polycarbonate-based diol.

[0059] First, examples of the polycarbonate-based diol include diols obtained by transesterification of alkylene glycol with carbonate ester, or by reaction of phosgene or chloroformate with alkylene glycol.

[0060] Examples of alkylene glycols used in this polycarbonate-based diol include linear alkylene glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, and 1,10-decanediol, branched alkylene glycols such as neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, and 2-methyl-1,8-octanediol, alicyclic diols such as 1,4-cyclohexanediol, aromatic diols such as bisphenol A, glycerin, trimethylolpropane, and pentaerythritol. In this embodiment, either a polycarbonate-based diol obtained from a single alkylene glycol or a copolymer polycarbonate-based diol obtained from two or more alkylene glycols can be used.

[0061] The polyester-based diols include diols obtained by condensing various low-molecular-weight polyols with polybasic acids.

[0062] The low molecular weight polyol used in this polyester diol may be, for example, one or more selected from the group consisting of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, and adducts of various alkylene oxides added to bisphenol A.

[0063] Examples of the polybasic acid used in this polyester diol include one or more selected from the group consisting of succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, and hexahydroisophthalic acid.

[0064] Furthermore, examples of polyether diols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymer diols obtained by combining these.

[0065] When the polymeric elastomer is polyurethane, the number-average molecular weight of the polymer diol is preferably in the range of 500 to 4000, provided that the molecular weight of the polyurethane elastomer is constant. A number-average molecular weight of preferably 500 or more, more preferably 1500 or more, can prevent the artificial leather from becoming hard, resulting in a more flexible artificial leather. Furthermore, a number-average molecular weight of preferably 4000 or less, more preferably 3000 or less, can maintain the strength of the polyurethane, resulting in a stronger artificial leather.

[0066] Next, when the polymeric elastomer is polyurethane, examples of the organic diisocyanate include aliphatic diisocyanates such as "hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and xylylene diisocyanate," and aromatic diisocyanates such as "diphenylmethane diisocyanate and tolylene diisocyanate," and these can also be used in combination.

[0067] When the elastomer is polyurethane, the chain extender can be an amine-based chain extender such as ethylenediamine or methylenebisaniline, or a diol-based chain extender such as ethylene glycol. Alternatively, a polyamine obtained by reacting polyisocyanate with water can be used as the chain extender.

[0068] Furthermore, when the polymeric elastomer is polyurethane, a crosslinking agent can be used in combination to improve water resistance, abrasion resistance, hydrolysis resistance, etc. The crosslinking agent may be an external crosslinking agent added to polyurethane as a third component, or an internal crosslinking agent that preliminarily introduces reactive points that form a crosslinked structure into the polyurethane molecular structure. From the viewpoint of being able to form crosslinking points more uniformly within the polyurethane molecular structure and reducing a decrease in flexibility, it is preferable to use an internal crosslinking agent.

[0069] As the crosslinking agent, a compound having an isocyanate group, an oxazoline group, a carbodiimide group, an epoxy group, a melamine resin, a silanol group, or the like can be used.

[0070] In this embodiment, the mass proportion of the polymer elastomer in the artificial leather is 15% by mass or more and 40% by mass or less. By making the mass proportion of the polymer elastomer 15% by mass or more, preferably 18% by mass or more, and more preferably 21% by mass or more, the bonding between the fibers by the polymer elastomer can be strengthened. Furthermore, the artificial leather has high abrasion resistance. On the other hand, by making the mass proportion of the polymer elastomer 40% by mass or less, preferably 37% by mass or less, and more preferably 34% by mass or less, the artificial leather has excellent moldability and can easily conform to complex shapes.

[0071] The mass percentage of the polymeric elastomer in the artificial leather is measured and calculated using the following method: (1) Three test pieces, each 20 cm long and 20 cm wide, are randomly taken from the artificial leather, and the mass of each test piece is measured. (2) The test pieces are immersed in a solution that dissolves the polymeric elastomer (for example, dimethylformamide is used when the polymeric elastomer is polyurethane), and the polymeric elastomer is removed to obtain ultrafine fibers. (3) The mass of the collected ultrafine fibers is measured, and the mass percentage of the polymeric elastomer in the test piece is calculated using the following formula: Mass percentage (%) of polymeric elastomer in the test piece = {(mass of test piece) - (mass of ultrafine fibers)} / (mass of test piece) × 100 (formula) (4) The mass percentage (%) of the polymeric elastomer in each of the three test pieces is calculated, and the arithmetic average (%) is rounded to one decimal place.

[0072] Furthermore, the polymeric elastomer may contain various additives depending on the purpose, such as "inorganic or oxide-based" pigments, "phosphorus-based, halogen-based, or inorganic" flame retardants, "phenol-based, sulfur-based, or phosphorus-based" antioxidants, "benzotriazole-based, benzophenone-based, salicylate-based, cyanoacrylate-based, or oxalic acid anilide-based" ultraviolet absorbers, "hindered amine-based or benzoate-based" light stabilizers, hydrolysis-resistant stabilizers such as polycarbodiimides, plasticizers, antistatic agents, surfactants, coagulation adjusters, and dyes.

[0073] In the artificial leather of this embodiment, for example, in order to achieve both deep and uniform color development, it is also preferable that the polymer elastomer contains a black pigment. This black pigment can be a carbon-based black pigment such as "carbon black or graphite" or an oxide-based black pigment such as "a composite oxide of triiron tetroxide, copper, and chromium." It is particularly preferable that the black pigment be carbon black, as this makes it easier to obtain black pigments with a small particle size and provides excellent dispersibility in polymers.

[0074] When the polymeric elastomer contains a black pigment, the average particle size of the black pigment is more preferably 0.05 μm or more and 0.20 μm or less. The average particle size of the black pigment referred to here means the average particle size of the black pigment when it is present in the polymeric elastomer, which is generally called the secondary particle size, i.e., the average particle size in an aggregated state.

[0075] By setting the average particle size of the black pigment to preferably 0.05 μm or more, more preferably 0.07 μm or more, the black pigment is held within the polymeric elastomer, thereby preventing the pigment from falling off from the polymeric elastomer. This results in an artificial leather with excellent resistance to friction. Furthermore, by setting the average particle size of the black pigment to preferably 0.20 μm or less, preferably 0.18 μm or less, more preferably 0.16 μm or less, the black pigment can be made to have excellent dispersibility when impregnated with the polymeric elastomer, resulting in an artificial leather with little variation in hue.

[0076] When the polymeric elastomer contains a black pigment, the coefficient of variation (CV) of the particle size of the black pigment is preferably 75% or less.

[0077] When the coefficient of variation (CV) of the particle size of the black pigment is 75% or less, preferably 65% ​​or less, more preferably 60% or less, even more preferably 55% or less, and most preferably 50% or less, the particle size distribution becomes narrow, and the detachment of small particles from the surface of the polymeric elastomer and the precipitation of significantly aggregated particles in the impregnation tank are suppressed. In this embodiment, there is no particular restriction on the lower limit of the coefficient of variation of the particle size, but from the viewpoint of operability when impregnating the polymeric elastomer, 0.1% or more is preferred.

[0078] In this embodiment, the average particle size and coefficient of variation (CV) of the black pigment contained in the polymeric elastomer are calculated by the following method. (1) An ultrathin section having a thickness of 5 μm to 10 μm is prepared in the cross-sectional direction of a surface perpendicular to the longitudinal direction of the artificial leather. (2) The cross-section of the polymeric elastomer in the ultrathin section is observed at 10,000x magnification using a transmission electron microscope (TEM, such as the "H7700" model manufactured by Hitachi High-Technologies Corporation). (3) Using image analysis software (such as "WinROOF" manufactured by Mitani Corporation), the circle-equivalent diameters of 20 black pigment particle sizes within a 2.3 μm × 2.3 μm field of view of the observed image are measured. If there are fewer than 20 black pigment particles within the 2.3 μm × 2.3 μm field of view, the circle-equivalent diameters of all the black pigment particles present are measured. (4) Calculate the average (arithmetic mean) and coefficient of variation (CV) for the particle diameters measured at 20 points. In this embodiment, the coefficient of variation is calculated using the following formula: Coefficient of variation of particle diameter (%) = (standard deviation of particle diameter) / (arithmetic mean of particle diameter) × 100 (formula).

[0079] Furthermore, when the polymeric elastomer contains a black pigment, the content of the black pigment contained in the polymeric elastomer is preferably 0.01% by mass or more and 5.0% by mass or less, relative to the mass of the polymeric elastomer. By setting the pigment mass percentage to preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1.0% by mass or more, the artificial leather will have excellent dark color development. On the other hand, by setting the pigment mass percentage to 5.0% by mass or less, preferably 4.5% by mass or less, and more preferably 4.0% by mass or less, the artificial leather will have excellent physical properties, such as strength.

[0080] In this embodiment, the content of the black pigment contained in the polymeric elastomer is calculated by the following method: (1) The artificial leather is immersed in a mixed solution of phenol and tetrachloroethane to dissolve the ultrafine fibers, and the polymeric elastomer is collected. (2) The collected polymeric elastomer is dissolved using dimethylformamide or the like, and only the black pigment is extracted. (3) The extracted black pigment is subjected to evolved gas analysis, and a calibration curve for the evolved gas derived from the black pigment is created. (4) The polymeric elastomer contained in the artificial leather is dissolved using dimethylformamide or the like, and the dimethylformamide or the like is then removed, thereby solidifying the polymeric elastomer again. (5) The polymeric elastomer obtained in (4) is subjected to evolved gas analysis, and the content of the black pigment contained in the polymeric elastomer constituting the artificial leather is calculated from the detected intensity of the evolved gas derived from the black pigment and the calibration curve created in (3).

[0081] [Artificial Leather] The artificial leather of this embodiment has a substrate portion including the fiber-entangled body and the polymer elastomer, and a napped portion on at least one surface. Here, the substrate portion is a portion including the fiber-entangled body and the polymer elastomer, and corresponds to the portion of the "base sheet" described in the artificial leather manufacturing method below, whose surface is not ground when viewed in the thickness direction. The napped portion refers to the portion in which the ultrafine fibers are not held by the polymer elastomer but are present in a dispersed state, and corresponds to the portion of the "base sheet" described in the artificial leather manufacturing method below, whose surface is ground when viewed in the thickness direction.

[0082] The artificial leather of this embodiment has a napped portion on at least one surface, as exemplified in Fig. 1. Both surfaces may have napped portions. In order to achieve good surface quality after molding and from the viewpoint of design, it is preferable that the nap shape on this napped surface has a length and directional flexibility that is sufficient to leave a mark when the nap direction changes when the leather is run over with a finger, that is, to leave a so-called finger mark.

[0083] First, in the artificial leather of this embodiment, the area ratio of the polymer elastomer on at least one surface having a napped portion of the artificial leather is 0.01% or more and 3.00% or less. In other words, when both surfaces have napped portions, it is sufficient that at least one surface satisfies this range.

[0084] When the area ratio of the polymer elastomer on at least one surface of the artificial leather having the napped portion (hereinafter sometimes abbreviated as "area ratio of polymer elastomer on the surface") is 0.01% or more, preferably 0.05% or more, more preferably 0.10% or more, the ultrafine fibers present in the napped portion are moderately gripped by the polymer elastomer at the boundary between the napped portion and the substrate portion of the artificial leather, resulting in an artificial leather with excellent abrasion resistance. On the other hand, when the area ratio of the polymer elastomer on the surface is 3.00% or less, preferably 2.00% or less, more preferably 1.00% or less, the artificial leather maintains a dense and smooth surface quality and a good feel even after molding.

[0085] In order to set the area ratio of the polymeric elastomer on the surface of this artificial leather within a predetermined range, the widthwise expansion ratio of the polyvinyl alcohol-added sheet, the apparent density of the polyvinyl alcohol contained in the nonwoven sheet, the grinding conditions of the surface of the base sheet, the thickness t of the base part of the artificial leather, Ａ and the thickness of the raised part t Ｂ The ratio t Ａ / t Ｂ This can be achieved by adjusting the

[0086] Furthermore, it is preferable that the standard deviation of the area proportion of the polymer elastomer on at least one surface of the artificial leather having a napped portion (hereinafter sometimes abbreviated as "standard deviation of the area proportion of the polymer elastomer on the surface") is 25% or less. In other words, when both surfaces have napped portions, it is sufficient that at least one surface meets this range. If the standard deviation of the area proportion of the polymer elastomer on at least one surface of the artificial leather is preferably 25% or less, more preferably 23% or less, and even more preferably 20% or less, the artificial leather will maintain a dense and smooth surface quality at all locations after molding. Note that there is no particular lower limit for the standard deviation of the area proportion of the polymer elastomer on the cross section in this embodiment. However, it is preferable that it be 1% or more.

[0087] The standard deviation of the area proportion of the polymeric elastomer on the surface of this artificial leather can be kept within a specified range by adjusting the widthwise expansion ratio of the polyvinyl alcohol-added sheet, the apparent density of the polyvinyl alcohol contained in the nonwoven sheet, and the grinding conditions for the surface of the base sheet.

[0088] In this embodiment, the area percentage of the polymeric elastomer on the surface of the artificial leather and the standard deviation of the area percentage of the polymeric elastomer on the surface are calculated by the following method. (1) A test piece measuring 0.5 cm in length and 0.5 cm in width is randomly taken from the artificial leather and left to stand in saturated ruthenium tetroxide vapor for 4 hours. This allows the polyurethane exposed on the surface of the artificial leather to be electronically stained. (2) The surface of the artificial leather is coated with 1 nm of osmium atoms to make it conductive. (3) The surface of the artificial leather is observed at 100x magnification using a field emission scanning electron microscope (e.g., JEOL Ltd.'s "JSM-7800F Prime"). (4) The obtained SEM image is binarized using image analysis software such as "ImageJ" by the following method, and the area percentage of the polymeric elastomer on the surface of the artificial leather is calculated. (i) The SEM image is filtered. In the case of "ImageJ", the processing conditions are as follows: Bilateral Filter of the Bilateral Filter Fij plug-in: spatial radius: 3 range radius: 50 Number of filter processes: 5 (ii) Binarization is performed using the MaxEntropy method, and the black parts in the binarized SEM image are regarded as polymeric elastomers. (iii) The obtained binarized image (2560 x 1920 pixels) is divided into 32 x 32 pixel sections (4800 divisions in this case). Then, in the case of "ImageJ," the Analyze Particle function (a function for measuring particle size and area) is used. In the case of "ImageJ," the conditions are set as follows: Size = 0 - infinity, Circularity = 0.00 - 1.00), and the total area of ​​each polymer elastomer distributed within each compartment is divided by the area of ​​each compartment to obtain the area percentage (%) of the polymer elastomer exposed on the surface of each compartment. (iv) The number of pixels on the x and y axes of the target image is read, the compartment size is specified in pixel size, the number of divisions on the x and y axes is determined, and the area percentage of the polymer elastomer within each divided region is calculated. The area percentage (%) of the polymer elastomer on the surface of the artificial leather is the average area percentage (%) of the polymer elastomer for all compartments, and its standard deviation is an indicator of variation from the average value for all compartments.

[0089] However, the standard deviation is calculated for all the sections obtained by dividing one image into sections, but if 100 images are prepared, the average value and standard deviation of the area ratio (%) of the polymer elastomer on the surface are calculated for all the calculation results for all the sections of each of the 100 images (in the above case, (100 images) x (4,800 divisions) = 480,000 pieces).

[0090] An example of image analysis software is the image analysis software "ImageJ," but the image analysis software is not limited to the image analysis software "ImageJ" as long as it is image processing software having the function of calculating the area ratio of specified pixels. The image analysis software "ImageJ" is general-purpose software developed by the National Institutes of Health. The image processing software "ImageJ" has the function of identifying necessary areas in an imported image and performing pixel analysis.

[0091] Next, in this embodiment, the area ratio of the polymer elastomer in the cross section of the artificial leather is 5% or more and less than 15%. When the area ratio of the polymer elastomer in the cross section of the artificial leather (hereinafter sometimes abbreviated as "area ratio of the polymer elastomer in the cross section") is 5% or more, more preferably 7% or more, and even more preferably 9% or more, the polymer elastomer sufficiently bonds between the fibers, resulting in an artificial leather having good strength and abrasion resistance while suppressing breakage of the artificial leather during molding processing. On the other hand, when the area ratio of the polymer elastomer in the cross section is less than 15%, more preferably 14% or less, and even more preferably 13% or less, the artificial leather has excellent moldability and can easily follow complex shapes.

[0092] Furthermore, it is preferable that the standard deviation of the area ratio of the polymer elastomer in the cross section of the artificial leather is 25% or less. When the standard deviation of the area ratio of the polymer elastomer in the cross section of the artificial leather is preferably 25% or less, more preferably 23% or less, and even more preferably 20% or less, every part of the artificial leather can uniformly conform to complex shapes during molding processing, resulting in an artificial leather that not only has excellent moldability but also maintains a dense and smooth surface quality. In this embodiment, there is no particular lower limit for the standard deviation of the area ratio of the polymer elastomer in the cross section. However, it is preferable that it is 1% or more.

[0093] In this embodiment, the area ratio of the polymeric elastomer in the cross section of the artificial leather and the standard deviation of the area ratio of the polymeric elastomer in the cross section are calculated by the following method. (1) A test piece measuring 0.5 cm in length and 1.0 cm in width is randomly taken from the artificial leather, and the internal space is embedded in an epoxy resin. (2) The resin-embedded test piece is cut parallel to the thickness direction using a microtome. (3) The cut test piece is left to stand in saturated ruthenium tetroxide vapor for 4 hours. This causes the polymeric elastomer in the cross section of the artificial leather to be electronically stained. (4) The cross section of the artificial leather is coated with 1 nm of osmium atoms to make it conductive. (5) The cross section of the artificial leather is observed at 500x magnification using a field emission scanning electron microscope (e.g., the "JSM-7800F Prime" manufactured by JEOL Ltd.). (6) The obtained SEM image is binarized using, for example, image analysis software such as "ImageJ" by the following method, and the area ratio (%) of the polymer elastomer in the cross section of the artificial leather is calculated: (i) The SEM image is filtered. For "ImageJ," the processing conditions are as follows: "Band-pass filter processing" (processing that removes high and low spatial frequency components) Filter large structures down to 40 pixels Filter small structures up to 3 pixels Suppression sizes: None Tolerance of direction: 5% Autoscale after filtering: Yes Saturate image when autoscaling: Yes Number of filter processes: 1 "Median filter processing" (processing that reduces image noise by replacing each pixel value with the median of the pixel values ​​in its vicinity) Radius: 4.0 Number of filter processes: 1 (ii) Binarization is performed using the MaxEntropy method, and the black areas in the binarized SEM image are designated as polymeric elastomers. (iii) The resulting binarized image (1280 x 960 pixels) is divided into 32 x 32 pixel sections (1200 divisions in this case).Then, in the case of "ImageJ," its Analyze Particle function (a function for measuring particle size and area. In the case of "ImageJ," the conditions are set as follows: Size = 0 - infinity, Circularity = 0.00 - 1.00), and the total area of ​​each polymer elastomer distributed in each compartment is divided by the area of ​​each compartment to obtain the area percentage (%) of the polymer elastomer exposed in the cross section of each compartment. (iv) The number of pixels on the x and y axes of the target image is read, the compartment size is specified in pixel size, the number of divisions on the x and y axes is determined, and the area percentage of the polymer elastomer in each divided region is calculated. The area percentage (%) of the polymer elastomer in the cross section of the artificial leather is the average area percentage (%) of the polymer elastomer for all compartments, and its standard deviation is an indicator of variation from the average value for all compartments.

[0094] However, the standard deviation is calculated for all the sections obtained by dividing one image into sections, but if 100 images are prepared, the average value and standard deviation of the area ratio (%) of the polymer elastomer in the cross section are calculated for all the calculation results for all the sections of each of the 100 images (in the above case, (100 images) x (1200 divisions) = 120,000 pieces).

[0095] Furthermore, the thickness t of the base material Ａ is 250 μm or more and 800 μm or less, and the thickness t of the base material Ａ and the thickness of the raised part t Ｂ Ratio to t Ａ / t Ｂ By satisfying these two requirements, localized tearing of the artificial leather during molding processing can be suppressed, and the artificial leather can be made to have excellent abrasion resistance while maintaining a dense and smooth surface quality.

[0096] First, the thickness t of the base material Ａ The thickness t of the substrate is preferably 250 μm or more and 800 μm or less. Ａ is preferably 250 μm or more, more preferably 300 μm or more, so that the artificial leather can be formed while suppressing localized breakage of the artificial leather and maintaining a dense and smooth surface quality.Ａ By making the thickness preferably 800 μm or less, more preferably 700 μm or less, an artificial leather can be obtained that can uniformly conform to complex shapes during molding processing.

[0097] Next, the thickness t of the base material of the artificial leather Ａ and the thickness of the raised portion t Ｂ The ratio t Ａ / t Ｂ It is preferable that the ratio t is 0.5 or more and 2.5 or less. Ａ / t Ｂ By setting the ratio t to be preferably 0.5 or more, more preferably 0.7 or more, the artificial leather can be made to have excellent abrasion resistance while maintaining a uniform and dense surface quality. Ａ / t Ｂ By making the ratio of the surface area of ​​polyurethane exposed on the surface of the artificial leather less, the artificial leather can be made smooth to the touch while the ratio of the surface area of ​​polyurethane exposed on the surface of the artificial leather being less.

[0098] The thickness t of the base material Ａ It is preferable that the coefficient of variation of the thickness t of the substrate portion is 50% or less. Ａ When the coefficient of variation of is preferably 50% or less, more preferably 25% or less, and even more preferably 10% or less, the artificial leather can be uniformly conformed to a complex shape while suppressing localized breakage of the artificial leather during molding, and can maintain a dense and smooth surface quality. Ａ The lower limit of the coefficient of variation is not particularly limited.

[0099] In addition, the thickness of the piled portion t Ｂ The average length of the napped portion is preferably 300 μm or more, more preferably 350 μm or more, so that the area ratio of the polymeric elastomer exposed on the surface of the artificial leather can be reduced while making the artificial leather smooth to the touch. Ｂ By making the thickness preferably 500 μm or less, more preferably 450 μm or less, an artificial leather having excellent abrasion resistance while maintaining a uniform and dense surface quality can be obtained.

[0100] Furthermore, the thickness t Ｂ It is preferable that the coefficient of variation of the thickness t of the raised portion is 50% or less. Ｂ When the coefficient of variation of is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less, the area ratio of the polymeric elastomer exposed on the surface of the artificial leather is reduced, and it becomes easier to fall within the above range, resulting in an artificial leather that achieves both a uniform and dense surface quality and a smooth touch. Ｂ The lower limit of the coefficient of variation is not particularly limited, but is preferably 1% or more.

[0101] In this embodiment, the thickness t Ａ and its standard deviation, the thickness of the raised part t Ｂ The standard deviations of the thickness and the thickness of the artificial leather are measured and calculated by the following method. (1) Using a lint brush or the like, the nap of the artificial leather is raised, and a thin section of 1 mm in thickness is prepared in the cross-sectional direction perpendicular to the longitudinal direction of the artificial leather. (2) The cross-section of the artificial leather is photographed at 90x magnification using a scanning electron microscope (SEM, for example, "VHX-D500 / D510" manufactured by Keyence Corporation). (3) In the SEM image, the bottom surface of the artificial leather (the L in FIG. 2) is photographed according to the schematic diagram of the cross-section of the artificial leather shown in FIG. Ｂ ) parallel to the line (L in FIG. 2) Ａ (4) Draw perpendicular lines on the surface of the substrate (2 in FIG. 2) at intervals of 200 μm. ０ ) point P １ ~P １０ (5) Mark point P １ ~P １０ Draw perpendicular lines (dotted lines in Figure 2) in the direction of the raised portion and the direction of the base material, respectively, and intersect with the end of the raised portion at point Q １ ~Q １０ and the point S at which it intersects with the end of the substrate １ ~S １０ (6) Point P １ and S １ Distance T １ Similarly, T １０ The average value (arithmetic mean value) (μm) is rounded to the first decimal place to determine the thickness t of the substrate portion.Ａ (μm). Then, the thickness t of the substrate portion is calculated by the following formula: Ａ Calculate the coefficient of variation (%) of the thickness of the substrate t Ａ Coefficient of variation (%) = (thickness of the substrate t Ａ (distance T １ ~Distance T １０ ) / (standard deviation (μm) of the thickness of the substrate t Ａ (distance T １ ~Distance T １０ ) arithmetic mean value (μm) × 100 ... (formula). (7) Point P １ and Q １ Distance R １ Similarly, R １０ The average value (arithmetic mean value) (μm) is rounded off to the first decimal place to determine the thickness t of the napped portion. Ｂ Then, the thickness t of the raised portion is calculated by the following formula: Ｂ Calculate the coefficient of variation (%) of the thickness of the napped portion t Ｂ Coefficient of variation (%) = (thickness of the napped portion t Ｂ (Distance R １ ~Distance R １０ ) standard deviation (μm)) / (thickness of the napped portion t Ｂ (Distance R １ ~Distance R １０ ) arithmetic mean value (μm) × 100 ... (formula).

[0102] In this embodiment, the weight of the artificial leather is 150 g / m ２ 450g / m or more ２ The weight of the artificial leather is preferably 150 g / m or less. ２ More preferably, 175 g / m ２ By satisfying the above conditions, the artificial leather can be made excellent in strength and abrasion resistance while suppressing breakage during molding processing. ２ or less, more preferably 400 g / m ２ By satisfying the above condition, the artificial leather can be made to conform uniformly to complex shapes during molding processing.

[0103] The basis weight of the artificial leather of this embodiment is measured in accordance with "6.2 Mass per unit area (ISO method)" of JIS L1913:2010 "Testing methods for general nonwoven fabrics," and is specifically measured and calculated as follows: (1) Three test pieces, each 30 cm long and 30 cm wide, are taken from the artificial leather. (2) The mass of the test pieces in (1) is measured. (3) The mass per unit area of ​​each test piece is calculated using the following formula: Mass per unit area (g / m ２ ) = mass of test piece (g) / area of ​​test piece (m ２ ) ... (Equation). (4) The arithmetic mean value of the mass per unit area obtained in (3) (g / m ２ ) is rounded down to the nearest whole number and the resulting value is the basis weight of the artificial leather.

[0104] The artificial leather of this embodiment preferably has a thickness of 0.5 mm or more and 1.2 mm or less, as measured by "6.1.1 Method A" of "6.1 Thickness (ISO Method)" of JIS L1913:2010 "Testing Methods for General Nonwoven Fabrics." By having a thickness of preferably 0.5 mm or more, more preferably 0.6 mm or more, the artificial leather has excellent strength and abrasion resistance while suppressing localized tearing of the artificial leather during molding. On the other hand, by having a thickness of preferably 1.2 mm or less, more preferably 1.0 mm or less, the artificial leather can be made to conform uniformly to complex shapes during molding.

[0105] The artificial leather of this embodiment preferably has a rub fastness measured by "9.1 Rub Tester Type I (Crockmeter) Method" of JIS L0849:2013 "Test Method for Color Fastness to Rub" and a light fastness measured by "7.2 Exposure Method a) First Exposure Method" of JIS L0843:2006 "Test Method for Color Fastness to Xenon Arc Lamp Light" of Grade 3 or higher. Having rub fastness and light fastness of Grade 3 or higher results in artificial leather that is less likely to fade or stain clothing during actual use. To determine each grade, the stain gray scale specified in JIS L0805:2005 "Stain Gray Scale" is used for the rub fastness of the artificial leather, and the discoloration gray scale specified in JIS L0804:2004 "Discoloration Gray Scale" is used for the light fastness of the artificial leather.

[0106] The friction resistance of this artificial leather is determined by the area ratio of the polymeric elastomer exposed on the surface of the artificial leather, the thickness t of the raised part on the surface of the artificial leather, Ｂ It is believed that by adjusting the coefficient of variation thereof to a specific range, friction between the naps can be reduced, the naps can be prevented from falling off, and the rub fastness can be improved.

[0107] Furthermore, in an abrasion resistance test for the artificial leather of this embodiment, measured according to "8.19.5 E Method (Martindale Method)" in "8.19 Abrasion Resistance and Friction Discoloration" of JIS L1096:2010 "Testing Methods for Woven and Knit Fabrics," the artificial leather is abraded 20,000 times with a pressing load of 12.0 kPa, and the mass loss of the artificial leather after abrasion is preferably 10 mg or less, more preferably 8 mg or less, and even more preferably 6 mg or less. A mass loss of 10 mg or less can prevent contamination due to fluff shedding during actual use.

[0108] Regarding the abrasion resistance of this artificial leather, in order to keep the mass loss of the artificial leather within a predetermined range after 20,000 times of abrasion at a pressing load of 12.0 kPa, the area ratio of the polymer elastomer on the surface of the artificial leather, the thickness t of the raised portion on the surface of the artificial leather, ＢIt is believed that by adjusting the coefficient of variation of the thickness of the fibers to a specific range, friction between the fibers can be reduced, and the mass loss can be suppressed.

[0109] The artificial leather of the present embodiment preferably has a tensile strength of 25 N / cm or more and 100 N / cm or less in any measurement direction, as measured in accordance with "6.3.1 Tensile strength and elongation (ISO method)" of JIS L1913:2010 "Testing methods for general nonwoven fabrics."

[0110] When the tensile strength is preferably 20 N / cm or more, more preferably 30 N / cm or more, the resulting artificial leather has excellent shape stability and durability. When the tensile strength is preferably 90 N / cm or less, more preferably 80 N / cm or less, the artificial leather can conform uniformly to complex shapes during molding and has a good texture.

[0111] [Method for Producing Artificial Leather] The artificial leather of this embodiment is preferably produced by either the following first or second production method.

[0112] That is, a first manufacturing method, which is one of the preferred embodiments, comprises the steps of: imparting polyvinyl alcohol to a fiber-entangled body containing a nonwoven fabric mainly composed of ultrafine fiber-developing fibers in an amount of 4% by mass to 40% by mass, relative to the mass of the ultrafine fiber-developing fibers, to form a polyvinyl alcohol-imparted sheet; expressing ultrafine fibers having an average single fiber diameter of 0.01 μm to 10.00 μm from the ultrafine fiber-developing fibers of the polyvinyl alcohol-imparted sheet, to form a nonwoven sheet; expanding the width of the nonwoven sheet by 2% to 10% to form an expanded sheet; imparting a polymeric elastomer to the expanded sheet in an amount of 12% by mass to 64% by mass, relative to the mass of the expanded sheet, to form a polymeric elastomer-imparted sheet; removing the polyvinyl alcohol from the polymeric elastomer-imparted sheet, to form a base sheet; and grinding at least one surface of the base sheet.

[0113] a second manufacturing method, which is another preferred embodiment, includes the steps of: imparting polyvinyl alcohol to a fiber-entangled body containing a nonwoven fabric mainly composed of ultrafine fiber-developing fibers in an amount of 4% by mass to 40% by mass, relative to the mass of the ultrafine fiber-developing fibers, to form a polyvinyl alcohol-imparted sheet; expanding the width of the polyvinyl alcohol-imparted sheet by 2% to 10% to form an expanded sheet; expressing ultrafine fibers having an average single fiber diameter of 0.01 μm to 10.00 μm from the ultrafine fiber-developing fibers of the expanded sheet to form a nonwoven sheet; imparting a polymeric elastomer to the nonwoven sheet in an amount of 12% by mass to 64% by mass, relative to the mass of the nonwoven sheet, to form a polymeric elastomer-imparted sheet; removing the polyvinyl alcohol from the polymeric elastomer-imparted sheet to form a base sheet; and grinding at least one surface of the base sheet.

[0114] The difference between the <first production method> and the <second production method> is the timing at which the ultrafine fibers are formed, and each method will be described in detail below.

[0115] <First manufacturing method> In this <First manufacturing method>, after forming a polyvinyl alcohol-imparted sheet described below, ultrafine fibers are developed before the sheet is widened. In this way, the load on the equipment for widening the sheet can be further reduced, and the sheet can be widened more uniformly in the width direction, and an artificial leather can be obtained that has formability that allows it to easily conform to complex shapes, and further has excellent surface quality and abrasion resistance after molding.

[0116] <Step of forming a polyvinyl alcohol-imparted sheet> In this step, polyvinyl alcohol is imparted to a fiber-entangled body containing a nonwoven fabric mainly composed of ultrafine fiber-developing fibers in an amount of 4% by mass to 40% by mass, relative to the mass of the ultrafine fiber-developing fibers, to form a polyvinyl alcohol-imparted sheet.

[0117] Here, ultrafine fiber-developing fibers refer to fibers that can be made into ultrafine fibers by the method described below. Specifically, examples include islands-in-sea composite fibers, in which thermoplastic resins with different solvent solubilities are used to form a sea portion (easily soluble polymer) and an island portion (slightly soluble polymer), and the sea portion is dissolved and removed using a solvent or the like to form ultrafine fibers from the island portion. Alternatively, peel-type composite fibers, in which two thermoplastic resin components with different solvent solubilities are alternately arranged radially or in multiple layers on the fiber cross section and the components are peeled and split into ultrafine fibers, are included. Among these, islands-in-sea composite fibers are more preferred from the viewpoint of the texture and surface quality of artificial leather, and because appropriate voids can be created between the island portions, i.e., between the ultrafine fibers within the fiber bundle, when the sea portion is removed. The produced ultrafine fiber-developing fibers are sometimes generally referred to as raw cotton.

[0118] As a method for spinning ultrafine fiber-producing fibers having an islands-in-sea composite structure, a method using a spinneret for islands-in-sea composite fibers and a polymer mutually aligned structure in which sea parts and island parts are mutually aligned and spun is preferred from the viewpoint of obtaining ultrafine fibers with a uniform single fiber diameter.

[0119] In this embodiment, in order to achieve both a darker and more uniform color development, a black pigment can be incorporated into the ultrafine fiber-forming fiber in the portion that will become the ultrafine fiber (in the case of an islands-in-sea composite fiber, the portion corresponding to the island portion). This can be achieved by spinning thermoplastic resin chips into which the black pigment has been pre-mixed, for example, at a mass ratio of 0.1% to 5.0% by mass relative to the thermoplastic resin, or by mixing a masterbatch into the thermoplastic resin in which the black pigment has been pre-mixed at a mass ratio of 10.0% to 40.0% by mass relative to the thermoplastic resin, and then spinning the mixture. Among these, the method of mixing the thermoplastic resin chips with a masterbatch is preferred because it allows for the appropriate adjustment of the amount of pigment contained in the ultrafine fibers.

[0120] When a masterbatch is used to mix with thermoplastic resin chips, it is preferable to use a masterbatch in which the number average primary particle size of the black pigment contained in the masterbatch used is 0.01 μm or more and 0.05 μm or less and the coefficient of variation (CV) is 0.1% or more and 30.0% or less. By using a masterbatch with a primary particle size within the above range, the particle size (secondary particle size) and coefficient of variation (CV) in the ultrafine fibers can be kept within appropriate ranges.

[0121] For the sea portion of the islands-in-sea type composite fiber, polyethylene, polypropylene, polystyrene, copolymer polyesters copolymerized with sodium sulfoisophthalic acid or polyethylene glycol, and polylactic acid can be used. From the viewpoints of spinnability and ease of elution, however, polystyrene and copolymer polyesters are preferably used.

[0122] When the ultrafine fiber-developing fiber is an islands-in-sea type composite fiber, it is preferable to use an islands-in-sea type composite fiber whose island portions have a tensile strength (tensile strength of the ultrafine fibers) of 2.2 cN / dtex or more. By making the tensile strength of the island portions preferably 2.2 cN / dtex or more, more preferably 3.0 cN / dtex or more, and even more preferably 4.0 cN / dtex or more, the abrasion resistance of the artificial leather can be improved and a decrease in friction fastness due to fiber shedding can be suppressed.

[0123] In this embodiment, the tensile strength of the island portions of the islands-in-sea type composite fiber (tensile strength of the ultrafine fibers) is calculated by the following method: (1) Ten islands-in-sea type composite fibers, each 20 cm long, are bundled together. (2) The sea portion is dissolved and removed from the sample obtained in (1), and then the sample is air-dried. (3) Ten tests are conducted (N=10) under the conditions of a grip length of 5 cm, a pulling speed of 5 cm / min, and a load of 2 N according to "8.5.1 Standard Time Test" in "8.5 Tensile Strength and Elongation" of JIS L1013:2010 "Testing Methods for Chemical Fiber Filament Yarns." (4) The arithmetic mean value (cN / dtex) of the test results obtained in (3) is rounded to one decimal place, and the resulting value is the tensile strength of the island portions of the islands-in-sea type composite fiber, i.e., the tensile strength of the ultrafine fibers.

[0124] In this process, the spun ultrafine fiber-developing fibers are opened and then formed into a fiber web using a cross wrapper or the like, and entangled to obtain a nonwoven fabric. Methods for entangling the fiber web to obtain a nonwoven fabric include needle punching and water jet punching.

[0125] As for the form of the nonwoven fabric, either a short fiber nonwoven fabric or a long fiber nonwoven fabric can be used, as described above. Among these, a short fiber nonwoven fabric has more fibers oriented in the thickness direction of the artificial leather than a long fiber nonwoven fabric, and can give the artificial leather a dense surface when raised.

[0126] When a staple fiber nonwoven fabric is selected as the nonwoven fabric, the obtained ultrafine fiber-developing fibers are preferably subjected to crimping processing, cut to a predetermined length to obtain raw cotton, and then opened, laminated, and entangled to obtain a staple fiber nonwoven fabric. Known methods can be used for crimping and cutting.

[0127] Furthermore, when the fiber-entangled body for the artificial leather contains a woven fabric, the obtained nonwoven fabric and the woven fabric are laminated and integrated. The nonwoven fabric and the woven fabric can be entangled and integrated by laminating the woven fabric on one or both sides of the nonwoven fabric, or by sandwiching the woven fabric between multiple nonwoven fabric webs and then entangling the fibers of the nonwoven fabric and the woven fabric by needle punching, water jet punching, or the like.

[0128] The apparent density of the nonwoven fabric made of ultrafine fiber development type fibers after needle punching or water jet punching is 0.15 g / cm ３ 0.35g / cm or more ３ The apparent density is preferably 0.15 g / cm or less. ３ More preferably, 0.20 g / cm ３ By setting the apparent density to 0.35 g / cm or more, the artificial leather can have sufficient shape stability and dimensional stability, and localized breakage during molding processing can be suppressed. ３ or less, more preferably 0.30 g / cm ３By setting the above, it is possible to maintain a sufficient space for providing the polymeric elastomer, and to keep the area ratio of the polymeric elastomer in the cross section of the artificial leather within a predetermined range.

[0129] It is also a preferred embodiment that the nonwoven fabric is subjected to a heat shrinking treatment using hot water or steam in order to improve the denseness of the fibers.

[0130] Next, polyvinyl alcohol is added to the fiber-entangled body in an amount of 4% by mass to 40% by mass, based on the mass of the ultrafine fiber-developing fiber, to form a polyvinyl alcohol-added sheet. By adding polyvinyl alcohol, the area ratio of the polymeric elastomer in the cross section of the final artificial leather can be set within a predetermined range, and an artificial leather can be obtained that has excellent formability that allows it to easily conform to complex shapes, a dense and uniform surface quality, abrasion resistance, and texture. One method for adding polyvinyl alcohol is to impregnate the fiber-entangled body with an aqueous solution of polyvinyl alcohol and then dry it to add polyvinyl alcohol.

[0131] In the present embodiment, it is preferable to form a polyvinyl alcohol-added sheet by adding 4% by mass or more and 40% by mass or less of the mass of the ultrafine fiber-developing fiber. By adding this amount of polyvinyl alcohol preferably at least 4% by mass, more preferably at least 8% by mass, and even more preferably at least 16% by mass, the polyvinyl alcohol fixes the fibers in the step of forming the polymeric elastomer-added sheet, thereby improving dimensional stability, and the thickness t Ａ On the other hand, by setting the amount of polyvinyl alcohol to be added to preferably 40% by mass or less, more preferably 32% by mass or less, and even more preferably 24% by mass or less, in the step of adding the polymeric elastomer, the presence of polyvinyl alcohol moderates the adhesion between the fibers and the polymeric elastomer, while the area ratio of the polymeric elastomer in the cross section of the artificial leather is set within a predetermined range, and the artificial leather can be molded to uniformly conform to complex shapes and have a good texture.

[0132] In this step, it is preferable to contain polyethylene glycol in an amount of 0.01% by mass or more and 0.5% by mass or less relative to the mass of the polyvinyl alcohol. By making the polyethylene glycol content preferably 0.01% by mass or more, more preferably 0.1% by mass or more, foaming of the water-soluble resin can be suppressed and the preparation time can be shortened when preparing the aqueous solution of the water-soluble resin. On the other hand, by making the polyethylene glycol content preferably 0.5% by mass or less, more preferably 0.3% by mass or less, polyvinyl alcohol can be imparted to the fiber-entangled body in uniform size, and the area ratio of the polymeric elastomer in the cross section of the finally obtained artificial leather can be within a predetermined range.

[0133] <Step of Forming Nonwoven Sheet> In this step, ultrafine fibers having an average single fiber diameter of 0.01 μm or more and 10.00 μm or less are produced from the ultrafine fiber-producing fibers of the polyvinyl alcohol-imparted sheet, to form a nonwoven sheet.

[0134] Ultrafine fibers having an average single fiber diameter within the above range can be produced from the ultrafine fiber-producing fibers of the polyvinyl alcohol-imparted sheet by, for example, immersing the polyvinyl alcohol-imparted sheet in a solvent. When the ultrafine fiber-producing fibers are islands-in-sea composite fibers, the production can be achieved by, for example, dissolving and removing the sea portion.

[0135] When the ultrafine fiber-developing fiber is an islands-in-sea type composite fiber, the solvent for dissolving and removing the sea portion can be an organic solvent such as toluene or trichloroethylene if the sea portion is made of polyethylene, polypropylene, or polystyrene. Alternatively, an aqueous alkali solution such as sodium hydroxide can be used if the sea portion is made of a copolymer polyester or polylactic acid. Alternatively, hot water (water at 70°C to 99°C) can be used if the sea portion is made of a water-soluble thermoplastic polyvinyl alcohol resin.

[0136] Furthermore, by repeatedly immersing the polyvinyl alcohol-imparted sheet in a solvent and squeezing and compressing the sheet with a mangle, ultrafine fibers can be efficiently produced from the ultrafine fiber-producing fibers.

[0137] Another preferred embodiment of the treatment for dispersing the generated ultrafine fibers is to pass a water current through the interior of the nonwoven sheet in a liquid. This water current applies mechanical impact to the bundled ultrafine fibers, thereby dispersing the ultrafine fibers. Specifically, a device such as a vibro washer is used. This vibro washer is preferred because it can perform a uniform dispersion treatment over the entire surface of the nonwoven sheet.

[0138] <Step of forming an expanded sheet> In this step, the width of the nonwoven sheet is expanded by 2% to 10% to form an expanded sheet.

[0139] By increasing the width of the nonwoven sheet by preferably 2% or more, more preferably 3% or more, the adhesion between the ultrafine fibers and the polyvinyl alcohol is relaxed, and the adhesion between the ultrafine fibers and the polymeric elastomer can be adjusted in the process of forming the polymeric elastomer-imparted sheet described below. As a result, an artificial leather can be obtained that can uniformly conform to complex shapes during molding. On the other hand, by increasing the width of the nonwoven sheet by preferably 10% or less, more preferably 8% or less, the nonwoven sheet can be uniformly expanded in the width direction while reducing the equipment load. Furthermore, the apparent density of the polyvinyl alcohol contained in the nonwoven sheet can be appropriately reduced, and the area ratio of the polymeric elastomer in the cross section and surface of the finally obtained artificial leather can be within a predetermined range.

[0140] <Step of Forming a Polymeric Elastomer-Provided Sheet> In this step, a polymeric elastomer is provided to the wide-width sheet in an amount of 12% to 64% of the wide-width sheet's mass to form a polymeric elastomer-provided sheet. More specifically, the wide-width sheet is preferably impregnated with a solution of a polymeric elastomer precursor so that the amount provided is 12% to 64% of the wide-width sheet's mass, and then solidified to form a polymeric elastomer-provided sheet. Here, the polymeric elastomer precursor refers to a precursor (hereinafter sometimes simply referred to as "precursor") that becomes a polymeric elastomer by means such as coagulation or solidification, as described below. For example, when the polymeric elastomer is polyurethane, the polyurethane precursor is a mixture of the polyurethane's reactive components, i.e., polymer diol, organic diisocyanate, chain extender, etc.

[0141] In this embodiment, in order to achieve both a darker and more uniform color development, a polymeric elastomer containing a black pigment can be applied to the wide sheet. For example, a method for this purpose may be used, such as incorporating the black pigment into a precursor of the polymeric elastomer. The black pigment used preferably has a number-average primary particle diameter of 0.01 μm or more and 0.05 μm or less, and a coefficient of variation (CV) of 0.1% or more and 30.0% or less. By using a black pigment with a primary particle diameter within the above range, the particle diameter (secondary particle diameter) and coefficient of variation (CV) in the polymeric elastomer can be kept within appropriate ranges.

[0142] As a solvent used when applying the polymeric elastomer to the fiber-entangled body, N,N'-dimethylformamide, dimethyl sulfoxide, etc. may be preferably used. Alternatively, an aqueous dispersion in which the polymeric elastomer is dispersed in water as an emulsion may be used.

[0143] <Step of Forming a Base Sheet> In this step, the polyvinyl alcohol is removed from the sheet provided with the elastomer to form a base sheet. This can be done by immersing the sheet provided with the elastomer in water heated to 65°C to 95°C (hot water) and then drying the sheet.

[0144] The step of forming this base sheet can also be carried out simultaneously with the step of forming a sheet with elastomer imparted thereto. That is, the polyvinyl alcohol can be removed by immersing the fiber-entangled body in hot water in addition to the step of removing the solvent, such as N,N'-dimethylformamide or dimethyl sulfoxide, used when imparting the elastomer to the fiber-entangled body. In this embodiment, even in such a case, both the step of forming a sheet with elastomer imparted thereto and the step of forming a base sheet are considered to have been carried out.

[0145] <Step of Grinding At Least One Surface of the Base Sheet> In this step, at least one surface of the base sheet is ground. This imparts nap to the surface, forming a napped portion. For this grinding, it is preferable to use a grinding means such as sandpaper or a roll sander. Furthermore, from the viewpoint of production efficiency, it is also a preferred embodiment to cut the base sheet in half in the thickness direction to form two sheets prior to this grinding. Note that this grinding can be performed on only one side surface of the sheet or on both sides. However, when grinding a sheet cut in half in the thickness direction, it is preferable to grind the newly formed surface (half surface) formed by cutting in half.

[0146] In order to obtain an artificial leather that maintains excellent surface quality even after molding, the base sheet is ground by grinding means in multiple stages, preferably two or more times, more preferably three or more times. Furthermore, it is more preferable that the grit size of the sandpaper or roll sander used in each stage be gradually finer, or at least be the same.

[0147] The grain size of the sandpaper or roll sander used to grind the surface of the substrate sheet (corresponding to the surface of artificial leather) is preferably in the range of #100 or more and #320 or less as specified in JIS R6610:2000 "Grain size of abrasives for abrasive cloths." By setting the grain size of the sandpaper or roll sander to preferably #100 or more, more preferably #120 or more, the thickness t of the napped portion can be reduced. Ｂ By setting the grit size of the sandpaper or roll sander to preferably no. 320 or less, more preferably no. 240 or less, it is possible to obtain artificial leather with a dense feel and uniform and elegant surface quality.

[0148] When at least one surface of the base sheet is ground multiple times by the grinding means, the conveying speed of the base sheet is preferably 10 m / min or more and 20 m / min or more. By setting the conveying speed of the base sheet to preferably 10 m / min or more, more preferably 13 m / min or more, the thickness t of the napped portion can be reduced while achieving good productivity. Ｂcan be kept within a predetermined range. On the other hand, by setting the conveying speed of the base sheet preferably to 20 m / min or less, more preferably to 17 m / min or more, it is possible to keep the area ratio of the polymeric elastomer on the surface of the artificial leather within a predetermined range while suppressing the load on the equipment, and to achieve a dense and uniform surface quality even after molding. The conveying speed of the base sheet referred to here means the speed at which the sheet is fed to a roll rotating sandpaper at high speed or a roll sander.

[0149] The grinding speed is preferably 200 m / min or more and 1000 m / min or less. By setting the grinding speed to preferably 200 m / min or more, more preferably 300 m / min or more, the thickness t of the napped portion can be increased while suppressing the load on the equipment. Ｂ is within a predetermined range, thereby producing an artificial leather with an excellent touch. On the other hand, by setting the grinding speed preferably to 1000 m / min or less, more preferably to 900 m / min or less, the area ratio of the polymer elastomer on the surface of the artificial leather can be set within a predetermined range, thereby achieving a dense and uniform surface quality even after molding. The grinding speed here refers to the peripheral speed calculated from the rotational speed and peripheral length of the sandpaper or roll sander, and can be calculated specifically by the following formula: Grinding speed (m / min) = {rotational speed of the sandpaper or roll sander (rpm / min)} × {peripheral length of the sandpaper or roll sander (m / rpm)} ... (formula).

[0150] Before grinding, a lubricant such as a silicone emulsion can be applied to the surface of the substrate sheet. Also, by applying an antistatic agent before grinding, grinding dust generated from the artificial leather during grinding is less likely to accumulate on the sandpaper.

[0151] Here, the basis weight of the ground sheet material obtained after the grinding was 150 g / m ２ 450g / m or more ２ The basis weight of the sheet-like material obtained after grinding is preferably 150 g / m or less. ２ More preferably, 175 g / m ２By setting the weight of the sheet to 450 g / m, it is possible to suppress the breakage of the sheet during this process as well as during the molding process, and to produce an artificial leather excellent in strength and abrasion resistance. ２ or less, more preferably 400 g / m ２ By satisfying the following conditions, an artificial leather can be obtained that can uniformly conform to complex shapes during molding processing.

[0152] In the second manufacturing method, a polyvinyl alcohol-imparted sheet (described later) is formed, and then the sheet is expanded to form ultrafine fibers. This process makes it possible to obtain an artificial leather that has formability that allows it to easily conform to more complex shapes, excellent surface quality after molding, and a soft feel.

[0153] <Step of forming a polyvinyl alcohol sheet> This step is exactly the same as in the first production method.

[0154] <Step of forming an expanded sheet> This step is basically the same as the <Step of forming an expanded sheet> in <First manufacturing method>, except that while the <Step of forming an expanded sheet> in <First manufacturing method> widens a nonwoven sheet in which ultrafine fibers are expressed, in this step, the width of the polyvinyl alcohol-added sheet is widened by 2% to 10% to form an expanded sheet. For details, the term "nonwoven sheet" in the <Step of forming an expanded sheet> in <First manufacturing method> can be explained by replacing the term "nonwoven sheet" with "polyvinyl alcohol-added sheet."

[0155] <Step of forming nonwoven sheet> This step is basically the same as the <Step of forming nonwoven sheet> in <First manufacturing method>, except that while the <Step of forming nonwoven sheet> in <First manufacturing method> involves widening a polyvinyl alcohol-imparted sheet before ultrafine fibers are expressed, this step involves widening ultrafine fibers having an average single fiber diameter of 0.01 μm or more and 10.00 μm or less from the ultrafine fiber-expressing fibers in the widened sheet to form a nonwoven sheet. For details, the term "polyvinyl alcohol-imparted sheet" in <Step of forming nonwoven sheet> in <First manufacturing method> can be explained by replacing the term "widened sheet" with "widened sheet."

[0156] <Step of forming a polymeric elastomer-imparted sheet> This step is basically the same as the <Step of forming a polymeric elastomer-imparted sheet> in <First manufacturing method>, except that while the polymeric elastomer is imparted to an expanded sheet in the <Step of forming a polymeric elastomer-imparted sheet> in <First manufacturing method>, in this step, the polymeric elastomer is imparted to the nonwoven sheet in an amount of 12% to 64% of the mass of the nonwoven sheet to form a polymeric elastomer-imparted sheet. For details, the term "expanded sheet" in the <Step of forming a polymeric elastomer-imparted sheet> in <First manufacturing method> can be explained by replacing the term "expanded sheet" with "nonwoven sheet".

[0157] <Step of Forming Base Sheet> This step is exactly the same as in the first manufacturing method.

[0158] <Step of Grinding At Least One Surface of the Base Sheet> This step is exactly the same as in the first manufacturing method.

[0159] <Subsequent steps of the first and second manufacturing methods> Furthermore, following the <First manufacturing method> or the <Second manufacturing method>, the sheet obtained by grinding at least one surface of the base sheet can also be dyed.

[0160] Examples of dyeing methods that can be used include jet dyeing using a jigger dyeing machine or jet dyeing machine, dip dyeing such as thermosol dyeing using a continuous dyeing machine, or printing on napped surfaces using roller printing, screen printing, inkjet printing, sublimation printing, and vacuum sublimation printing. Jet dyeing machines are preferred in terms of quality and grade, as they provide a soft texture. If necessary, various resin finishing processes can be applied after dyeing.

[0161] The sheet obtained as described above can be used as artificial leather as is, but if necessary, various surface treatments can be applied to the sheet to produce artificial leather with excellent design. For example, post-processing such as perforation, embossing, laser processing, pinsonic processing, and printing can be applied. In addition, various resin finishing processes can be applied.

[0162] [Vehicle interior materials, vehicle parts, miscellaneous goods, furniture] The artificial leather of the present embodiment obtained by the production method exemplified above has both good formability that allows it to conform to complex shapes during molding and maintains a dense and smooth surface quality even after molding. Therefore, it is a material particularly suitable for applications such as vehicle interior materials and interiors.

[0163] First, vehicle interior materials containing the artificial leather are preferred because they can easily conform to complex shapes during molding, while maintaining a fine, smooth surface after molding. Such vehicle interior materials are preferably used for vehicle parts such as steering wheels, horn switches, shift knobs, dashboards, instrument panels, glove compartments, floor carpets, floor mats, ceiling linings, sun visors, and assist grips in automobiles, and it is more preferred that these vehicle parts contain the artificial leather. In this embodiment, the term "vehicle" refers to automobiles, aircraft, railroad vehicles, ships, carriages, carriages, rickshaws, and other vehicles, as well as some industrial, construction, and agricultural machinery capable of carrying humans or animals, such as excavators, cranes, tractors, and combines.

[0164] Furthermore, miscellaneous goods containing the artificial leather are also one of the preferred embodiments, including accessories such as shoes, hats, bags, belts, scarves, ties, and wallets, and interior goods such as cushions, armrests, and neck pillows.

[0165] The shoes include sneakers, pumps, loafers, boots, sandals, slippers, and spikes. Preferably, at least a portion of the upper, lining, insole, shoelaces, etc. of such shoes is made of the artificial leather.

[0166] Examples of the bag include handbags, tote bags, shoulder bags, Boston bags, waist pouches, briefcases, attaché cases, school bags, etc. It is preferable that at least a part of the handle, inner bag, base leather, gusset, bottom, etc. of such bags be made of the above-mentioned artificial leather.

[0167] Furthermore, furniture containing the artificial leather is also a preferred embodiment. Examples of such furniture include chairs, sofas, stools, etc. It is preferable that at least a portion of the seat, back, etc. of such furniture is made of the artificial leather.

[0168] Next, the artificial leather of this embodiment will be described in more detail using examples, but this embodiment is not limited to these examples.

[0169] [Measurement methods and processing methods for evaluation] Next, the evaluation methods and measurement conditions used in the examples will be explained. However, in measuring each physical property, unless otherwise specified, the measurement was carried out based on the above-mentioned method.

[0170] (1) Average Single Fiber Diameter (μm) of Ultrafine Fibers: In measuring the average single fiber diameter of ultrafine fibers, ultrafine fibers were observed using a scanning electron microscope (SEM) model "VHX-D500 / D510" manufactured by Keyence Corporation, and the average single fiber diameter was calculated.

[0171] (2) Tensile strength of ultrafine fibers (cN / dtex): The tensile strength of ultrafine fibers was measured using a Tensilon universal material testing machine "RTC-1350A" manufactured by A&D Co., Ltd., and was measured and calculated by the method described above.

[0172] (3) Thickness t of the base material of the artificial leather Ａ (μm) and its coefficient of variation (%): Thickness t of the base material of the artificial leather Ａ In the measurement, a scanning electron microscope (SEM) "VHX-D500 / D510" manufactured by Keyence Corporation was used to observe the cross section of the artificial leather, and the thickness t Ａ and the coefficient of variation was calculated.

[0173] (4) Thickness t of the raised portion of the artificial leather Ｂ (μm) and its coefficient of variation (%): Thickness t of the raised portion of the artificial leather Ｂ In the measurement, a scanning electron microscope (SEM) "VHX-D500 / D510" manufactured by Keyence Corporation was used to observe the cross section of the artificial leather, and the thickness t Ｂ and the coefficient of variation was calculated.

[0174] (5) Artificial leather basis weight (g / m ２ ): The basis weight of the artificial leather was measured and calculated by the above-mentioned method.

[0175] (6) Thickness of Artificial Leather (mm): The thickness of the artificial leather was measured and calculated using a thickness measuring device, "Peacock Dial Thickness Gauge H" manufactured by Ozaki Seisakusho Co., Ltd.

[0176] (7) Mass Proportion (% by mass) of Polymeric Elastomer: The mass proportion of the polymeric elastomer was measured and calculated using dimethylformamide as a solvent.

[0177] (8) Area ratio (%) of polymer elastomer on the surface of the side having the napped portion of the artificial leather and its standard deviation (%): In the above measurement, a field emission scanning electron microscope "JSM-7800F Prime" manufactured by JEOL Ltd. was used, and further, measurement and calculation were carried out using "ImageJ" as image analysis software.

[0178] (9) Area ratio (%) of polymer elastomer in cross section of artificial leather and its standard deviation (%): In the above measurement, a field emission scanning electron microscope "JSM-7800F Prime" manufactured by JEOL Ltd. was used, and further, measurement and calculation were carried out using "ImageJ" as image analysis software.

[0179] (10) Tensile strength (N / cm) of artificial leather: Two 2 cm x 20 cm test pieces were taken in any direction of the artificial leather, and the tensile strength (N / cm) was measured as specified in "6.3.1 Tensile strength and elongation (ISO method)" of JIS L1913:2010 "Test methods for general nonwoven fabrics." The average of the two pieces was used as the tensile strength of the artificial leather. The measurement was performed using an Instron single-column tabletop testing machine "3343."

[0180] (11) Friction fastness (grade) of artificial leather: The degree of staining of the sample after the rubbing test was judged using the above-mentioned staining gray scale, and the result was grade 4 or higher (L ＊ a ＊ b ＊ Color difference ΔE according to color system ＊ ａｂ A value of 4.5±0.3 or less was considered acceptable.

[0181] (12) Lightfastness (grade) of artificial leather: After irradiating the sample with xenon arc light, the degree of discoloration of the sample was graded using the above-mentioned gray scale for discoloration, and graded to 4 or higher (L ＊ a ＊ b ＊ Color difference ΔE according to color system ＊ ａｂ The value was 1.7±0.3 or less, which was considered to be acceptable.

[0182] (13) Lightness of artificial leather (L ＊ Value, no unit): Using a spectrophotometer, JIS Z8781-4:2013 "Colorimetry - Part 4: CIE1976L ＊ a ＊ b ＊ The L* value defined in "3.3 CIE1976 Lightness Index" of the "Color Space" was measured. The measurement was carried out 10 times using a "CM-M6" manufactured by Konica Minolta, Inc., and the average of the measurements was used to determine the L* value of the artificial leather. ＊ The value was set as

[0183] (14) Abrasion resistance (mg) of artificial leather: The abrasion resistance test (measured by "8.19.5 E method (Martindale method)" in "8.19 Abrasion resistance and friction discoloration" of "JIS L1096:2010 "Testing methods for woven and knitted fabrics"] was carried out using a "Model 406" abrasion tester manufactured by James H. Heal & Co. Ltd. and an "Abrasive Cloth SM25" manufactured by the same company as the standard friction cloth, with a pressure load of 12.0 kPa and abrasion count of 20,000 times) was carried out. Artificial leathers with an abrasion loss of 10 mg or less were considered to have passed the test.

[0184] (15) Touch of Artificial Leather: The touch of the artificial leather was evaluated by the following sensory evaluation. Specifically, a total of 20 evaluators, 10 healthy adult males and 10 healthy adult females, evaluated the surface of the artificial leather having the napped portion according to the following evaluation criteria, and the most common evaluation was used to evaluate the touch of the artificial leather. In the case of a tie, the higher evaluation was used to evaluate the touch of the artificial leather. In this embodiment, a good level was rated as A or B. - A: A very smooth touch, with no catching sensation when stroking the surface. - B: A smooth touch, with only a slight catching sensation when stroking the surface. - C: A rough touch, with a catching sensation when stroking the surface. - D: A very rough touch, with a significant catching sensation when stroking the surface.

[0185] (16) Surface quality of artificial leather: The surface quality of the artificial leather was evaluated by the following sensory evaluation. Specifically, 20 evaluators, 10 healthy adult males and 10 healthy adult females, visually judged the following evaluations, and the most common evaluation was used to evaluate the surface quality of the artificial leather. In the event of a tie, the higher evaluation was used to evaluate the surface quality of the artificial leather. In this embodiment, the good level was rated as A or B. - A: Very dense and uniform surface quality. - B: Dense and uniform surface quality. - C: Poorly dense and highly variable surface quality. - D: Very poorly dense and highly variable surface quality.

[0186] (17) Coefficient of variation (%) of area change rate of artificial leather before and after molding: When artificial leather is used as a skin, the coefficient of variation of area change rate before and after molding was evaluated by the following methods (i) to (viii) as an index of surface quality after molding. A smaller value indicates more uniform deformation overall, and artificial leather with a coefficient of variation of area change rate of 30% or less was evaluated as artificial leather with excellent uniform deformability and good surface quality. (i) Ten evaluation samples of A4 size (210 mm x 297 mm) were randomly taken from the artificial leather. (ii) A 5 mm x 5 mm grid (grid) was drawn on the surface of the raised layer side of the taken evaluation sample. (iii) A 500 μm thick high-density polyethylene (PE) film was applied to the surface opposite to the raised layer side with the grid drawn, and a film-like olefin-based hot melt resin (thickness 50 μm, basis weight 20 g / m) was applied. ２ ) and laminated together. (iv) The evaluation sample laminated with the film was placed on a concave cylindrical mold having a diameter of 50 mm, a height of 14 mm, and an area development ratio of 212%, with the napped layer facing the mold, and vacuum molding was performed at room temperature. (v) The area of ​​the grid marked on the napped surface of the evaluation sample obtained by vacuum molding was measured. For the measurement, a digital microscope "VHX-5000" manufactured by Keyence Corporation was used, and the magnification was adjusted to 20 times to measure the above area. (vi) The area of ​​the measured grid (mm ２ ) to the original area before molding (5 mm × 5 mm = 25 mm ２ ) to obtain a percentage, and the area change rate (%) was calculated. (vii) The arithmetic mean and standard deviation of the area change rate (%) calculated for each square were calculated. (viii) The coefficient of variation (%) of the area change rate was calculated from the value calculated in (vii) using the following formula, and rounded to the first decimal place: Coefficient of variation (%) of area change rate = Standard deviation of area change rate / Arithmetic mean value of area change rate × 100 (formula).

[0187] (18) Area ratio (%) of polymer elastomer on the surface of the nap-side of artificial leather after molding: When the artificial leather is used as a skin, the area ratio of polymer elastomer on the surface of the nap-side of the artificial leather after molding was evaluated as an index of surface quality after molding. Artificial leathers with an area ratio of polymer elastomer of 3.00% or less on the surface of the nap-side of the artificial leather after molding were evaluated as having good surface quality, as they were able to suppress deterioration of surface quality due to increased exposure of polymer elastomer even after processing as a skin. (i) Of the squares entered on the surface of the nap-side of the molded product obtained by the area change rate (%) in (17), squares with an area change rate in the range of 145% to 155% were selected. Note that if there were no squares with an area change rate in the range of 145% to 155%, squares with an area change rate in the range of 135% to 144% or 156% to 165% were selected. (ii) Using the collected grid, the area percentage (%) of the polymer elastomer on the surface of the side having the napped portion of the artificial leather was measured in the same manner as in "(8) Area percentage (%) of the polymer elastomer on the surface of the side having the napped portion of the artificial leather."

[0188] (19) Surface quality of artificial leather after molding (points): Evaluation was carried out using evaluation samples after processing into a cylindrical shape as described in "(17) Coefficient of variation (%) of area change rate of artificial leather" above. Vacuum molding was carried out, and the resulting molded products were evaluated by 20 evaluators, 10 healthy adult males and 10 healthy adult females, to determine the surface quality of the artificial leather after processing using a five-point scale based on the following criteria. The surface quality of the artificial leather after processing was evaluated based on the total score given by each evaluator. Therefore, the total score ranged from a minimum of 20 points to a maximum of 100 points, with a score of 80 or more being considered acceptable.・5 points: Very good (the artificial leather is formed into a cylindrical shape, and there is no deterioration in quality due to increased exposure of the polymer elastomer on the surface of the artificial leather after processing). ・4 points: Good (between 5 and 3 points). ・3 points: Fair (the artificial leather is not formed into a cylindrical shape, or there is increased exposure of the polymer elastomer on the surface of the artificial leather after processing, and there is a deterioration in quality). ・2 points: Poor (between 3 and 1 point). ・1 point: Very poor (the artificial leather is not formed into a cylindrical shape, and there is a significant increase in exposure of the polymer elastomer on the surface of the artificial leather after processing, and there is a significant deterioration in quality).

[0189] Example 1 Step of Forming a Sheet with Polyvinyl Alcohol Added Thereto An ultrafine fiber-forming fiber having an islands-in-sea composite structure consisting of island parts and a sea part was melt spun under the following conditions: Island part: polyethylene terephthalate having an intrinsic viscosity (IV value) of 0.73 Sea part: polystyrene having an MFR (melt flow rate, measured according to the test method specified in ISO 1133:1997, the same applies hereinafter) of 65 g / 10 min Spinneret: spinneret for islands-in-sea composite fiber with 16 islands per hole Spinning temperature: 285°C Island part / sea part mass ratio: 80 / 20 Output rate: 1.2 g / min per hole Spinning speed: 1,100 m / min.

[0190] The ultrafine fiber-developing fiber was then stretched 2.7 times in a spinning oil bath at 90°C. The fiber was then crimped using a push-type crimper and cut to a length of 51 mm to obtain raw islands-in-sea composite fiber with a single fiber fineness of 4.2 dtex. The ultrafine fibers obtained from this islands-in-sea composite fiber had an average single fiber diameter of 4.40 µm and a strength of 3.7 cN / dtex.

[0191] The raw cotton thus obtained was subjected to carding and cross-wrapping processes to form a laminated web. ２ The fabric was needle punched with a number of punches of 470 g / m ２ Thus, a fiber-entangled structure containing a nonwoven fabric made of ultrafine fiber-developing fibers was obtained, which had a width of 183 cm and a thickness of 2.1 mm.

[0192] The fiber-entangled body obtained as described above was shrunk with hot water at 96°C. The nonwoven fabric shrunk with hot water was then impregnated with an aqueous polyvinyl alcohol solution with a saponification degree of 88% (this aqueous solution contained 0.13% by mass of polyethylene glycol relative to the mass of polyvinyl alcohol (hereinafter sometimes abbreviated as PVA)) prepared to a concentration of 12% by mass. The resulting sheet was then squeezed with a roll and dried with hot air at 120°C for 10 minutes to form a polyvinyl alcohol-imparted sheet in which the mass of PVA relative to the mass of the nonwoven fabric made of ultrafine fiber-developing fibers was 23% by mass.

[0193] <Step of forming nonwoven sheet> The obtained polyvinyl alcohol-imparted sheet was immersed in trichloroethylene, and then the steps of squeezing the liquid with a mangle and compressing were carried out 10 times, thereby dissolving and removing the sea portion of the ultrafine fiber-developing fiber and compressing the sheet, thereby forming a 158 cm wide nonwoven sheet in which ultrafine fibers with an average single fiber diameter of 4.40 μm were developed.

[0194] <Step of forming expanded sheet> Furthermore, this nonwoven sheet was expanded to a width of 163 cm using a pin tenter, that is, the width of the nonwoven sheet was expanded by 3%, to form an expanded sheet.

[0195] <Step of forming a polymeric elastomer-imparted sheet, step of forming a base sheet> The widened sheet obtained as described above was immersed in a DMF (dimethylformamide) solution of polyurethane, the polymer diol of which was a polycarbonate-based diol, prepared so that the solids concentration of the polymeric elastomer was 13.0%. The widened sheet immersed in the polyurethane DMF solution was then squeezed with a roll. Next, the sheet was immersed in a 30% by mass DMF aqueous solution to coagulate the polyurethane. At this point, the amount of polymeric elastomer imparted to the widened sheet was 27% by mass. The PVA and DMF were then removed with hot water at 95°C, and the sheet was dried with hot air at 100°C for 10 minutes. This resulted in a base sheet having a width of 153 cm, a thickness of 1.7 mm, and a polyurethane mass of 35% by mass relative to the mass of the ultrafine fibers.

[0196] <Step of Grinding At Least One Surface of the Base Sheet> The base sheet obtained as described above was cut in half so that each half had a thickness of 1 / 2. Subsequently, the conveying speed of the sheet-like material was set to 13 m / min, and the surface layer of the non-cut half was ground by 0.30 mm to perform a nap-raising treatment. The grinding speed was 900 m / min in the first stage and 700 m / min in the second stage, and endless sandpaper with a sandpaper count of 120 (referred to as "#120" in Tables 1 and 2; the same applies to other counts) was used as the grinding means. As a result, the ultrafine fibers had an average single fiber diameter of 4.40 μm, a width of 153 cm, and a basis weight of 200 g / m２ , a ground sheet having a thickness of 0.55 mm was obtained.

[0197] <Step of dyeing the ground sheet> The ground sheet was dyed in a jet dyeing machine and reduced and washed to obtain a dyed sheet. In this dyeing, a black dye was used, and the L of the dyed sheet was ＊ A recipe prepared so that the value would be 22 was used, and the temperature of the dyeing solution was set to 120° C. Thereafter, the dyeing solution was dried in a pin tenter at 100° C. for 7 minutes to obtain an artificial leather having a thickness of 0.65 mm and a mass proportion of the polymeric elastomer of 26 mass %.

[0198] The resulting artificial leather had a very dense feel, a uniform surface quality, a very smooth feel, and excellent abrasion resistance. Furthermore, the artificial leather after molding was formed into a cylindrical shape, and there was no deterioration in the surface quality of the artificial leather before and after molding. The results are shown in Tables 1 and 2.

[0199] [Example 2] In the <step of forming an expanded sheet>, an artificial leather was obtained in the same manner as in Example 1, except that a nonwoven sheet having a width of 158 cm was expanded to 161.5 cm as shown in Table 1, i.e., the width of the nonwoven sheet was expanded by 2%.

[0200] The resulting artificial leather had a dense feel, a uniform surface quality, a very smooth feel, and excellent abrasion resistance. Furthermore, the artificial leather after molding was formed into a cylindrical shape, and there was no deterioration in the surface quality of the artificial leather before and after molding. The results are shown in Tables 1 and 2.

[0201] [Example 3] In the <step of forming an expanded sheet>, an artificial leather was obtained in the same manner as in Example 1, except that a nonwoven sheet having a width of 158 cm was expanded to 172 cm as shown in Table 1, i.e., the width of the nonwoven sheet was expanded by 9%.

[0202] The resulting artificial leather had a very dense feel, a uniform surface quality, and a smooth feel. Furthermore, the artificial leather after molding was formed into a cylindrical shape, and there was no deterioration in the surface quality of the artificial leather before and after molding. The results are shown in Tables 1 and 2.

[0203] [Example 4] An artificial leather was obtained in the same manner as in Example 1, except that in the <step of forming a polyvinyl alcohol-imparted sheet>, ultrafine fiber-developing fibers having an islands-in-sea composite structure consisting of island parts and sea parts were melt-spun under the following conditions. Island component: A mixture of the following components P1 and P2 in a mass ratio of 95:5. P1: Polyethylene terephthalate having an intrinsic viscosity (IV value) of 0.73. P2: A masterbatch in which the polyethylene terephthalate A contains, as a black pigment, carbon black (average particle size: 0.02 μm, coefficient of variation (CV) of particle size: 20%) in an amount of 20 mass% relative to the mass of the masterbatch. Sea component: Polystyrene having an MFR (melt flow rate, measured in accordance with the test method specified in ISO 1133:1997) of 65 g / 10 min. Spinneret: A spinneret for islands-in-sea type composite fibers with 16 islands per hole. Spinning temperature: 285°C. Island / sea mass ratio: 80 / 20. Output rate: 1.2 g / min per hole. Spinning speed: 1,100 m / min.

[0204] The resulting artificial leather had a very dense feel, a uniform surface quality, a very smooth feel, and excellent abrasion resistance. Furthermore, the artificial leather after molding was formed into a cylindrical shape, and there was no deterioration in the surface quality of the artificial leather before and after molding. The results are shown in Tables 1 and 2.

[0205]

[0206]

[0207] [Example 5] An artificial leather was obtained in the same manner as in Example 1, except that in the <Step of forming a polyvinyl alcohol-added sheet>, as shown in Table 3, 4 mass % of PVA was added relative to the mass of the nonwoven fabric made of ultrafine fiber-developing fibers.

[0208] The resulting artificial leather had a dense feel, a uniform surface quality, a smooth feel, and excellent abrasion resistance. Furthermore, the artificial leather after molding was formed into a cylindrical shape, and there was no deterioration in the surface quality of the artificial leather before and after molding. The results are shown in Tables 3 and 4.

[0209] [Example 6] An artificial leather was obtained in the same manner as in Example 1, except that in the <Step of forming a polyvinyl alcohol-added sheet>, as shown in Table 3, 40 mass % of PVA was added relative to the mass of the nonwoven fabric made of ultrafine fiber-developing fibers.

[0210] The resulting artificial leather had a very dense feel, a uniform surface quality, and a smooth feel. Furthermore, the artificial leather after molding was formed into a cylindrical shape, and there was no deterioration in the surface quality of the artificial leather before and after molding. The results are shown in Tables 3 and 4.

[0211] [Example 7] An artificial leather was obtained in the same manner as in Example 1, except that in the <Step of forming a polyvinyl alcohol-added sheet>, as shown in Table 3, 48 mass% of PVA was added relative to the mass of the nonwoven fabric made of ultrafine fiber-developing fibers.

[0212] The resulting artificial leather had a dense feel, a uniform surface quality, and a smooth feel. Furthermore, the artificial leather after molding was formed into a cylindrical shape, and there was no deterioration in the surface quality of the artificial leather before and after molding. The results are shown in Tables 3 and 4.

[0213] [Example 8] An artificial leather was obtained in the same manner as in Example 1, except that in the <step of forming a polyvinyl alcohol sheet>, a nonwoven fabric that had been shrunk with hot water was impregnated with an aqueous PVA solution with a saponification degree of 88% (containing 0.60% by mass of polyethylene glycol relative to the mass of PVA) that had been adjusted to a concentration of 12% by mass as shown in Table 3.

[0214] The resulting artificial leather had a dense feel, a uniform surface quality, and a smooth feel. Furthermore, the artificial leather after molding was formed into a cylindrical shape, and there was no deterioration in the surface quality of the artificial leather before and after molding. The results are shown in Tables 3 and 4.

[0215]

[0216]

[0217] [Comparative Example 1] An artificial leather was obtained in the same manner as in Example 1, except that in the <step of forming an expanded sheet>, a nonwoven sheet having a width of 158 cm was not expanded but a polymeric elastomer was applied, as shown in Table 3.

[0218] The obtained artificial leather had a smooth feel, but the surface area ratio of the polymeric elastomer was high, the surface was not dense, and the surface quality was highly variable. Furthermore, the artificial leather after molding had a large coefficient of variation in the area change rate, and the polymeric elastomer was increasingly exposed on the surface of the artificial leather, indicating a deterioration in quality. The results are shown in Tables 5 and 6.

[0219] [Comparative Example 2] An artificial leather was obtained in the same manner as in Example 1, except that in the <Step of Forming an Expanded Sheet>, a nonwoven sheet with a width of 158 cm was expanded to 175 cm as shown in Table 3, i.e., the width of the nonwoven sheet was expanded by 11%. The obtained artificial leather had a smooth feel, but lacked a dense feel and had a surface quality with significant variation. In addition, localized tears occurred during the molding process, making it impossible to evaluate the coefficient of variation of the area change rate of the artificial leather and the area ratio of the polymer elastomer on the surface of the artificial leather. The results are shown in Tables 5 and 6.

[0220] [Comparative Example 3] In the <step of forming a nonwoven sheet>, a nonwoven sheet having a width of 158 cm was treated with a vibro washer, and a water current was passed through the interior of the nonwoven sheet in water to disperse the ultrafine fibers. In the <step of forming an expanded sheet>, as shown in Table 3, the 158 cm wide nonwoven sheet was not expanded but a polymeric elastomer was applied. An artificial leather was obtained in the same manner as in Example 1.

[0221] The obtained artificial leather had a smooth feel, but the surface area ratio of the polymeric elastomer was high, the surface was not dense, and the surface quality was highly variable. Furthermore, the artificial leather after molding had a large coefficient of variation in the area change rate, and the polymeric elastomer was increasingly exposed on the surface of the artificial leather, indicating a deterioration in quality. The results are shown in Tables 5 and 6.

[0222]

[0223]

[0224] As shown in Tables 1 to 4, in the artificial leathers of Examples 1 to 8, in the step of forming an expanded sheet, a nonwoven sheet to which PVA had been added at a predetermined ratio was expanded within a predetermined range, the adhesive state between the ultrafine fibers and the PVA was moderately relaxed, and then a polymeric elastomer was added and the sheet was ground, thereby setting the area ratio of the polymeric elastomer on the surface and cross section of the artificial leather within a specific range, thereby achieving both good formability that can follow complex shapes and a dense and smooth surface quality even after molding.

[0225] On the other hand, as shown in Tables 5 and 6, when the artificial leather of Comparative Example 1 was not subjected to the widening process in the step of forming the widened sheet, the area ratio of the polymer elastomer on the surface and cross section of the artificial leather fell outside the specified range, and it was not possible to achieve both formability capable of conforming to complex shapes and dense, smooth surface quality even after molding.

[0226] Furthermore, when the nonwoven sheet was expanded by more than 10% in the process of forming the expanded sheet, as in the artificial leather of Comparative Example 2, the area ratio of the polymer elastomer in the cross section of the artificial leather fell outside the specified range, and it was not possible to achieve both the formability to conform to complex shapes and the dense, smooth surface quality even after molding processing.

[0227] Furthermore, as in the artificial leather of Comparative Example 3, even when the ultrafine fibers were dispersed using a vibro washer in the process of forming the nonwoven sheet, if the widening was not performed in the process of forming the widened sheet, the area ratio of the polymer elastomer on the surface and cross section of the artificial leather fell outside the specified range, and it was not possible to achieve both the formability that can conform to complex shapes and the dense and smooth surface quality even after molding processing.

[0228] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2023-169362) filed on September 29, 2023, the entirety of which is incorporated by reference. All references cited herein are incorporated in their entirety.

[0229] 1: Artificial leather 2: Napped portion 3: Base material 4: Surface having the napped portion 5: Surface opposite to the surface having the napped portion (bottom surface) L Ａ : Line parallel to the bottom L Ｂ : Bottom L ０ : Boundary line between the piled part and the base material part P １ ~P １０ Q: Point on the boundary between the piled part and the base material part １ ~Q １０ : Point where the perpendicular line intersects with the end of the raised portion R １ ~R １０ : The distance between the point on the boundary between the raised portion and the base material portion and the point where the perpendicular line intersects with the end of the raised portion S １ ~S １０ : Point where the perpendicular line intersects with the edge of the base material T １ ~T １０ : The distance between the point where the perpendicular line intersects with the end of the piled portion and the point where the perpendicular line intersects with the end of the base material portion

Claims

1. An artificial leather having a base material including a fiber-entangled body including a nonwoven fabric made of ultrafine fibers having an average single fiber diameter of 0.01 μm or more and 10.00 μm or less, and a polymer elastomer, and a napped portion on at least one surface, wherein the mass ratio of the polymer elastomer to the artificial leather is 15 mass% or more and 40 mass% or less, the area ratio of the polymer elastomer to at least one surface of the artificial leather having the napped portion is 0.01% or more and 3.00% or less, and the area ratio of the polymer elastomer to a cross section of the artificial leather is 5% or more and less than 15%.

2. The artificial leather according to claim 1, wherein the standard deviation of the area ratio of the polymeric elastomer on at least one surface of the artificial leather having the napped portion is 25% or less.

3. The artificial leather according to claim 1 or 2, wherein the standard deviation of the area ratio of the polymeric elastomer in the cross section of the artificial leather is 25% or less.

4. Thickness t of the base material Ａ is 250 μm or more and 800 μm or less, and the thickness t Ａ and the thickness of the raised part t Ｂ Ratio to t Ａ / t Ｂ The artificial leather according to claim 1 or 2, wherein the value is 0.5 or more and 2.5 or less.

5. Thickness t of the base material Ａ The artificial leather according to claim 4, wherein the coefficient of variation of is 50% or less.

6. The artificial leather according to claim 1 or 2, wherein the microfibers contain a black pigment.

7. A method for producing artificial leather, comprising the steps of: imparting polyvinyl alcohol to a fiber-entangled body containing a nonwoven fabric mainly composed of ultrafine fiber-expressing fibers in an amount of 4% by mass to 40% by mass of the ultrafine fiber-expressing fibers to form a polyvinyl alcohol-imparted sheet; expressing ultrafine fibers having an average single fiber diameter of 0.01 μm to 10.00 μm from the ultrafine fiber-expressing fibers of the polyvinyl alcohol-imparted sheet to form a nonwoven sheet; widening the width of the nonwoven sheet by 2% to 10% to form an expanded sheet; imparting a polymer elastomer to the expanded sheet in an amount of 12% by mass to 64% by mass of the expanded sheet to form a polymer elastomer-imparted sheet; removing the polyvinyl alcohol from the polymer elastomer-imparted sheet to form a base sheet; and grinding at least one surface of the base sheet.

8. A method for producing artificial leather, comprising the steps of: imparting polyvinyl alcohol to a fiber-entangled body containing a nonwoven fabric mainly composed of ultrafine fiber-developing fibers in an amount of 4% by mass to 40% by mass, relative to the mass of the ultrafine fiber-developing fibers, to form a polyvinyl alcohol-imparted sheet; expanding the width of the polyvinyl alcohol-imparted sheet by 2% to 10% to form an expanded sheet; expressing ultrafine fibers having an average single fiber diameter of 0.01 μm to 10.00 μm from the ultrafine fiber-developing fibers of the expanded sheet to form a nonwoven sheet; imparting a polymer elastomer to the nonwoven sheet in an amount of 12% by mass to 64% by mass, relative to the mass of the nonwoven sheet, to form a polymer elastomer-imparted sheet; removing the polyvinyl alcohol from the polymer elastomer-imparted sheet to form a base sheet; and grinding at least one surface of the base sheet.

9. A method for producing an artificial leather as described in claim 7 or 8, wherein in the step of forming the polyvinyl alcohol sheet, polyethylene glycol is contained in an amount of 0.01% by mass or more and 0.5% by mass or less relative to the mass of the polyvinyl alcohol.

10. A vehicle interior material comprising the artificial leather according to claim 1 or 2.

11. A vehicle part comprising the artificial leather of claim 1 or 2.

12. Miscellaneous goods comprising the artificial leather according to claim 1 or 2.

13. Furniture comprising the artificial leather according to claim 1 or 2.

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